Finish the sentence: She has _____ knowledge of the subject.

The correct choice is "little," which fits the context of the sentence. "Little" is used with uncountable nouns, such as "knowledge." This suggests a small amount of knowledge about the subject, indicating that the person does not possess much familiarity or understanding.

In contrast, "few" and "a few" are used with countable nouns, which would not be appropriate in this context since "knowledge" is uncountable. "Some" could be a possibility; however, it implies an unspecified but more substantial amount than "little," making it less precise when the intent is to convey a limited understanding. Thus, "little" accurately conveys a small extent of knowledge, aligning well with the intended meaning of the sentence.