The answer ________ that no one knows.

The answer ________ that no one knows.

• A. are
• B. will
• C. is
• D. was

Answer: (C)

The phrase uses a singular subject, The answer, so the verb must be singular to match it. Is fits as the present simple link to the clause that follows, giving a factual statement: The answer is that no one knows. That that-clause contains no one knows, where no one is treated as singular and takes the singular verb knows, keeping the tense appropriate for a current assertion. The other options don’t fit because they disrupt agreement or tense: are would treat the subject as plural, will would require a future form like will be, and was would shift to past tense, which isn’t natural with the present fact stated here.

The phrase uses a singular subject, The answer, so the verb must be singular to match it. Is fits as the present simple link to the clause that follows, giving a factual statement: The answer is that no one knows.

That that-clause contains no one knows, where no one is treated as singular and takes the singular verb knows, keeping the tense appropriate for a current assertion.

The other options don’t fit because they disrupt agreement or tense: are would treat the subject as plural, will would require a future form like will be, and was would shift to past tense, which isn’t natural with the present fact stated here.