The correct answer is "URI." In Java, the URI class is used to represent a Uniform Resource Identifier. It's designed to handle the complete URI syntax, including components like scheme, authority, path, query, and fragment. A URI is a broader concept that includes URLs (Uniform Resource Locators) and URNs (Uniform Resource Names).

In Java, the submit method of the ExecutorService interface is used to submit a Callable task and returns a Future object representing the result of the computation. This method is commonly used for asynchronous tasks that return results.

In Java, constructors are special methods used to initialize objects. They have the same name as the class they belong to, making option 1 ("class") the correct choice. Constructors cannot have a return type.

The "%" (modulo) operator in Java is used to divide the left-hand operand by the right-hand operand and returns the remainder. For example, "10 % 3" returns 1 because 10 divided by 3 leaves a remainder of 1. The other operators perform different arithmetic operations.

In Java, when you create a HashMap without specifying an initial capacity, it defaults to an initial capacity of 16. This means that initially, the HashMap can accommodate 16 key-value pairs. However, as the number of entries increases and reaches a certain threshold (usually 75% of the capacity), the HashMap automatically resizes itself, doubling its capacity. So, option (a) is correct, with the explanation that it can ideally accommodate 16 entries initially but will resize when necessary.

When a method is overridden in the child class, the version of the method in the child class is called when the method is invoked on an instance of the child class. This is known as method overriding and is a fundamental concept in object-oriented programming.

To ensure thread safety in a multithreaded application, you can use synchronized methods for read and write operations on the shared User object. This prevents multiple threads from accessing and modifying the object simultaneously, avoiding data corruption and race conditions. The other options do not provide effective thread safety mechanisms.

Lambda expressions eliminate the need for anonymous inner classes. Before lambda expressions were introduced in Java, anonymous inner classes were used to implement single-method interfaces, like Runnable or ActionListener. Lambda expressions provide a more concise and expressive way to define such implementations, reducing the verbosity of code.

It uses type conversion to promote one of the operands to the type of the other operand, and then performs the operation. For example, if you add a string and an int, the int is converted to a string, and string concatenation is performed. If you add two integers, normal addition is performed.

In a text editor, where efficient memory and performance management are crucial, StringBuilder is used for in-place string manipulation, and WeakReference helps in memory management by allowing objects to be garbage collected when not strongly referenced. StringBuffer is thread-safe but may not provide the best performance. The other options are not suitable for such scenarios.