Statistics __________ a difficult subject for many students.

This question focuses on subject-verb agreement, particularly with nouns that end in "-s" but represent a singular concept or field of study. Words such as "statistics," "mathematics," "physics," "economics," and "news" are often treated as singular when they refer to an academic discipline or a body of knowledge, despite their plural appearance.

• A: are - "Are" is a plural verb. It would be correct if "statistics" referred to individual numerical facts or data points (e.g., "The statistics are misleading"). However, in this context, it refers to the subject itself.
• B: were - "Were" is a plural past tense verb, incorrect for the singular subject "statistics" as a field of study.
• C: is - "Is" is a singular present tense verb. This correctly agrees with "statistics" when it denotes the academic subject.
• D: have - "Have" is a plural verb (or used with "I" and "you"), incorrect for a singular subject.

Since the sentence refers to "Statistics" as an academic subject, similar to how one would say "Mathematics is a difficult subject," the singular verb "is" is required. The correct sentence is: "Statistics is a difficult subject for many students."