Two-factor authentication uses the combination of ""something you know"" with which other element?

The right answer is "something you have".

Explanation:

There are various types of authentication systems for web use.

Two-factor authentication is one of the main authentication system which uses the combination of "something you know" and "something you have" elements.

Here "something you know" refers to the credential a user uses to login i. e password, pin, etc.

While "something you have" refers to the hardware device or any taken which can be used to verify user's identity i. e OTP send on a phone or Email, smartcard, etc.