Question: What does the term "tree shaking" mean with regard to JavaScript performance?

1. only using code that is supported by the newest browsers, and serving the site without JavaScript to old browsers
2. removing unused code from the JavaScript files
3. splitting code into various bundles so that decisions can be made on loading priority
4. allowing the browser to ignore code it believes will perform badly

Answer: The correct answer of the above question is Option B:removing unused code from the JavaScript files