…… are used to identify a user who returns to a website.

A cookie is a small text file stored on a user's device by a website.

Cookies are used to:

Identify returning users
Remember login information
Store user preferences
Track browsing sessions

For example, when you log in to a website and it remembers you on your next visit, cookies are often responsible for that functionality.

Therefore, the correct answer is:

Answer: D) Cookies