Which of the following is the proper way to link to an external JavaScript file?

Linking to an external JavaScript file using the script element is typically done using the src attribute, which specifies the URL of the external script file. The proper syntax for this is <script src="file.js"></script>. This syntax allows the browser to fetch and execute the JavaScript code defined in the "file.js" file, which is crucial for structuring and maintaining clean code in web development.

The src attribute is important because it tells the browser where to find the JavaScript to be executed. Without it, the script tag would not know what code to run. Other variations, such as having "file.js" enclosed in quotes within the tag without the src attribute or using incorrect attribute names, would not work properly because they do not conform to the HTML standards for linking JavaScript files. Therefore, the correct choice accurately represents the appropriate HTML syntax to achieve the desired functionality.