The Access-Control-Allow-Methods header in CORS specifies which HTTP methods are allowed for cross-origin requests. It should include a comma-separated list of HTTP methods such as GET, POST, PUT, DELETE, etc.

Improper handling of dependencies and devDependencies can lead to larger bundle sizes when deploying an application. When you include unnecessary dependencies, your application's bundle size increases, impacting load times and performance.

In Express.js, to serve static files, you generally use the static middleware. This middleware allows you to serve files such as images, CSS, and JavaScript to clients.

To optimize the loading of modules in a large-scale application, you should use lazy loading (Option b). Lazy loading allows modules to be loaded only when they are needed, reducing initial load times and improving performance. Minification (Option a) is also a valid optimization technique but may not address the issue of slow initial loading. Increasing server resources (Option c) and reducing the number of modules (Option d) are not effective solutions for optimizing module loading.

In Express.js, an efficient way to handle multiple HTTP methods and optional parameters is to implement a single route handler and use conditional logic to differentiate between methods and handle optional parameters within the handler. This approach minimizes code duplication and keeps your codebase clean and maintainable. Using app.all (Option 1) would capture all HTTP methods and may lead to less control and more complex code. Separating handlers for each combination (Option 2) can result in code redundancy, making it harder to maintain. Creating multiple endpoints (Option 4) can lead to a cluttered route structure.

When implementing asynchronous middleware in Express.js, it's crucial to ensure that the middleware either returns a Promise or uses a callback to signal when it has completed its work. This is necessary to prevent premature termination of the request-response cycle and maintain proper error handling. Using await is a common approach to handling asynchronous operations.

To uninstall a package and also remove it from the package.json file, you should use the npm uninstall (or npm remove) command followed by the package name. This command removes both the package and its reference from package.json. The other options are not used for this specific purpose.

In a production build, it's important to exclude devDependencies as they are typically only needed for development and testing. Including them in production builds can increase the size of the application unnecessarily. Option (2) is a good practice, but not directly related to managing dependencies for production. Option (1) is incorrect as including all dependencies in devDependencies is not a best practice for production builds. Option (4) is risky as it may introduce compatibility issues.

In Node.js, you can create a buffer instance using the Buffer.alloc(size) method, where size is the desired size of the buffer in bytes. The new Buffer() constructor is deprecated, and the other options are not valid ways to create a buffer in Node.js.

Full-text search is most appropriately used when searching for specific keywords within a large body of text, such as searching for documents or articles containing certain words or phrases. It allows for complex text-based queries, making it ideal for content-heavy applications.