Respuesta :
Answer:
'Had Bought'
Explanation:
The infinitive 'to buy' turns into 'had bought' in past perfect. The PAST TENSE is simply 'bought', but the PAST PERFECT tense is 'had bought'.
i believe the answer is just "bought" because it is the past tense of "buy" and thats what the question is asking for-the past tense of "buy"