He ______ a packet of cigarettes a day ?

The correct answer to the sentence "He ______ a packet of cigarettes a day" is C) "smokes." This choice is appropriate because it grammatically fits the structure and meaning of the sentence.

Let’s break it down:

1. Subject-Verb Agreement: The subject of the sentence is "He," which is a singular third-person pronoun. In English, when the subject is third-person singular, verbs in the present tense typically take an "s" at the end, as in "smokes."

2. Present Simple Tense Usage: The present simple tense is used to describe habitual actions or routines. The sentence indicates a regular behaviorsmoking a packet of cigarettes daily. Therefore, the use of "smokes" appropriately conveys that this is something he regularly does.

3. Analysis of Other Options:
- A) "smoking" is the gerund form and does not fit grammatically in this context.
- B) "were smoking" is the past continuous tense which implies an ongoing action in the past, not suited here.
- D) "smoke" is the base form of the verb and does not agree with the singular subject "He."

In summary, "smokes" is correct because it maintains the necessary subject-verb agreement and accurately describes a habitual action in the present tense.