Final answer:
The adjective 'consuming' is the correct choice to complete the sentence, meaning that basketball fully occupies the subject's interest or passion.
Step-by-step explanation:
The correct answer to the question "Basketball is his ... passion." is consuming. The sentence is looking for an adjective that describes something that fully occupies or engrosses someone, i.e., their passion. Therefore, the correct sentence is "Basketball is his consuming passion." The other options, 'consumption', 'consumer', and 'consumerism', do not fit contextually as they relate to the act of consuming, a person who consumes, or the protection or promotion of the consumer's interests, respectively.