Final answer:
The 22nd amendment specifies that a person cannot be elected to the office of the President more than twice. This was a response to FDR's four terms and seeks to limit the total years a President can serve to ten years.
Step-by-step explanation:
The 22nd amendment states that no person shall be elected to the office of the President more than twice. This means that the correct answer is (b) Twice. The amendment, ratified in 1951, was a direct response to President Franklin D. Roosevelt being elected to four terms, which resulted in a change to the US Constitution to limit presidential terms. Furthermore, if someone becomes President or acts as President for more than two years of a term that someone else was elected to, they can only be elected President once more.
There is, however, a debate regarding whether someone who is no longer eligible to be elected President could be elected Vice President, according to the Twelfth Amendment qualities. It's important to note that this amendment ensures that no President can serve more than a total of ten years in office, accounting for the possibility of serving two years of another President's term before being elected to their own two full terms.