Topic: Article,

Best Answer Explained in Below-:

The sentence 'He lost __ few books he had' needs a determiner that correctly modifies the noun 'few books.' Among the options provided, 'a' is the most suitable choice.

When we use 'a few,' it conveys a positive quantity that suggests some, but not many—implying that the speaker acknowledges having had a small number of books. This aligns with the context of the sentence, indicating the person has lost a small number of books rather than none at all.

In contrast, if we consider the other options:

- 'the' implies a specific quantity known to the listener, which doesn't fit since it's not clear how many books he lost.
- 'some' suggests an indefinite number but doesn’t appropriately fit the context of 'few,' which highlights a countable limit.
- 'one' definitively indicates a singular book, altering the meaning and specifying rather than generalizing.

Thus, 'a few' is the optimal choice, communicating that he lost a small number of books without being overly specific. This captures the intended meaning of the sentence effectively.