Which amendment limits the number of terms a President can serve?

The 22nd Amendment to the United States Constitution specifically limits the number of terms a President can serve to two. This amendment was ratified in 1951 in response to Franklin D. Roosevelt's four terms in office, reflecting a desire to prevent any future president from holding excessive power by serving more than two terms. The language of the amendment clearly states that no person shall be elected to the office of the President more than twice, establishing a firm limit on presidential tenure.

In contrast, the 25th Amendment deals with presidential succession and disabilities, the 20th Amendment addresses the terms of the President and Congress, and the 21st Amendment repealed Prohibition. Each of these amendments serves a different purpose, but only the 22nd explicitly limits presidential terms, making it the correct answer to this question.