Final answer:
In a federal election, nobody must be told how you voted as it's confidential. This ensures that individuals can vote freely and without pressure from others. The secret ballot system in use in the U.S. is designed to uphold this confidentiality.
Step-by-step explanation:
When asked, who must you tell how you voted in a federal election? The answer is a) Nobody, it's confidential. The process of voting in federal elections is private, and you are not required to disclose your vote to anyone. This confidentiality is a cornerstone of the democratic process and ensures that all individuals can cast their votes without pressure or influence from others.
Elections in the United States currently use the Australian ballot system, which provides for secret voting to prevent coercion and to ensure the integrity of the electoral process. There are two types of Australian ballots used in the U.S.: the office-block ballot and the party-column ballot. Both methods allow for private and confidential voting.