To send JSON data as a response using the http module in Node.js, you should use response.write(JSON.stringify(jsonData)). This method writes the JSON data as a string to the response. The other options are not valid methods for sending JSON data in the http module.

In EJS, you can include partial views using the <%- include('partial') %> syntax. This allows you to reuse and insert content from other EJS files into your main template, helping you create modular and maintainable views. The other options are not the correct syntax for including partials in EJS.

The response.end() method is used to end the response process in an HTTP server. It finalizes the response and sends it to the client. The other options are not valid methods for ending the response.

To install a specific version of a package using npm, you should use the npm install @ command. This allows you to specify the exact version you want to install. The other options do not provide the same functionality or may not work as expected.

In arrow functions, the value of 'this' is inherited from the surrounding lexical context, which means it refers to the 'this' value of the containing function or block. Unlike regular functions, arrow functions do not have their own 'this' binding.

A primary feature of testing frameworks like Mocha or Jest is Test Automation. These frameworks allow developers to write and run automated tests to verify that their code works correctly. This includes unit tests, integration tests, and more.

The primary role of the app object in an Express application is to handle routing and middleware functions. It defines the routes for handling different HTTP requests (GET, POST, etc.) and can use middleware to add functionality to these routes, such as authentication or error handling. The other options do not accurately describe the role of the app object in Express.

To optimize the rendering performance of template engines like EJS and Pug, enabling caching is a common approach. This allows the templates to be compiled once and reused, reducing rendering time. Additionally, minimizing template complexity and avoiding synchronous rendering can also improve performance. However, completely avoiding template engines may not be practical in many web applications.

In semantic versioning, the 'minor' version should be incremented when new features or functionality are added in a backward-compatible manner. This indicates to users that they can safely update to the new version without worrying about breaking changes.

Creating a custom error class in Express.js is useful when you want to provide additional metadata with the error, such as error codes, status codes, or custom properties. This allows you to convey more context about the error to the client or developer. The other options are not typical use cases for custom error classes.

The primary use of the Events module in Node.js is to facilitate event-driven programming. It allows you to create, emit, and handle custom events, making it a fundamental part of building real-time and responsive applications. Options A, B, and D are not the primary purposes of the Events module.

To secure user passwords, it's best practice to store them using a hashing algorithm. Hashing takes the password and transforms it into a fixed-size string of characters (hash) using a one-way function. This makes it difficult to reverse-engineer the password from the stored hash.