15 I ______ new wireless headphones. I'm sure I'll use them to listen both to music and audio-books.

Solution:

The sentence describes the purchase of headphones, implying a completed action in the past that has relevance to the present. The present perfect tense is suitable here.

1. 'have bought' is the present perfect tense, indicating a past action with present relevance.
2. 'have been buying' is the present perfect continuous tense, suggesting a repeated action over a period.
3. 'haven't bought' is the negative present perfect tense.

The speaker has acquired the headphones, and the certainty of using them points to a completed purchase. 'Have bought' fits best.

Answer: A have bought