Nobody __________ willing to take responsibility.

This question tests subject-verb agreement, specifically with indefinite pronouns. Indefinite pronouns like "nobody," "somebody," "everybody," "anyone," "no one," "everyone," "someone," "each," and "either" are always considered singular, even though they might seem to refer to multiple people. Therefore, they require a singular verb to maintain grammatical correctness.

• A: are - "Are" is a plural verb, which does not agree with the singular subject "nobody."
• B: were - "Were" is a plural past tense verb, also incorrect for a singular subject.
• C: is - "Is" is a singular present tense verb, which correctly agrees with the singular indefinite pronoun "nobody."
• D: have - "Have" is a plural verb (or used with "I" and "you"), incorrect for a singular subject.

The correct choice is "is" because it is the singular form of the verb "to be" and properly matches the singular subject "Nobody." The sentence should read: "Nobody is willing to take responsibility."