In PHP, to define a class when using Object-Oriented Programming (OOP), you would use the class keyword followed by the name of the class. The correct option is "Using the class keyword." For further details, refer to the PHP documentation on defining classes: http://php.net/manual/en/language.oop5.php

In PHP, you can set a cookie using the setcookie() function. This function allows you to set the name, value, expiration time, path, domain, and other parameters for the cookie. Learn more: http://php.net/manual/en/function.setcookie.php

The scope of variables refers to the visibility or accessibility of variables within different parts of the code. It determines where and for how long a variable can be accessed. Learn more: http://php.net/manual/en/language.variables.scope.php

The statement is true. In PHP, the preg_match() function is used to perform a pattern match using Regular Expressions. It returns true if the pattern was found in the string and false otherwise. The preg_match() function allows you to search for a specific pattern within a string and perform further actions based on the result. This function is commonly used in PHP to check if a string matches a particular pattern defined by a Regular Expression. Learn more: https://www.php.net/manual/en/function.preg-match.php

The get_magic_quotes_gpc() function in PHP checks if magic quotes are enabled for the GPC (GET, POST, COOKIE) data. Magic quotes was a feature in older PHP versions that automatically added slashes before certain characters in GPC data to escape them. However, this feature is deprecated and removed in PHP versions 5.4 and later. The get_magic_quotes_gpc() function can be used to check if magic quotes were enabled on the server. It returns 1 if magic quotes were enabled, and 0 otherwise. It's important to note that using magic quotes is not recommended for security reasons. If magic quotes are enabled, you should disable them and properly sanitize and escape user input using appropriate functions and techniques.

The correct option is 2. PHP superglobals, such as $_POST, $_GET, and $_SERVER, are accessible from any part of the script, including both within and outside functions. Superglobals are automatically available in all scopes and can be accessed from anywhere within your PHP script without the need for special considerations or modifications. They provide important information and resources that are needed across different parts of the script, making them globally accessible. It is important to note that superglobals can be accessed from both functions and other parts of the script. Learn more: https://www.php.net/manual/en/language.variables.superglobals.php

To access a constant of a class in PHP, you can use the class name followed by the scope resolution operator :: and the constant name. For example: ClassName::CONSTANT_NAME This allows you to directly reference the value of a constant defined within a class without the need for object instantiation. The self keyword can also be used to access the constant within the class itself. To learn more, visit: http://php.net/manual/en/language.oop5.constants.php

To establish a connection to a MySQL database in PHP using the mysqli extension, you would use the mysqli_connect function. It takes four parameters: the host, username, password, and database name. These parameters are used to connect to the MySQL server and select the desired database. The function returns a connection object ($conn in this case) that can be used for further database operations. Ensure you provide the correct credentials and appropriate server details to establish a successful connection.

To troubleshoot an error when performing a network-related task using a PHP function, you can check the error message returned by the error_get_last() function. This function retrieves the last PHP error message. Reviewing this error message can provide insights into the issue that occurred during the function execution. Additionally, you can consider updating the PHP version and related extensions or reinstalling the PHP interpreter if the issue persists. By following these troubleshooting steps, you can identify and resolve the error encountered while performing a network-related task using a PHP function.

All of the given options can be done using either echo or print in PHP. Both echo and print can be used to output strings, variables, and HTML code. They can concatenate multiple strings together and display the result of an expression. The choice between echo and print depends on the specific requirements and personal preference. Learn more: https://www.php.net/manual/en/function.echo.php https://www.php.net/manual/en/function.print.php