Answer:
B. Credit note.
Step-by-step explanation:
A credit note is a document issued by the seller to the buyer, acknowledging that the buyer has returned a faulty item and providing credit for the value of the item. In this case, since only one unit out of the 40 purchased was faulty, HH would be entitled to receive a credit note for the value of that particular faulty unit. The credit note can then be used by HH to offset the cost of future purchases or to obtain a refund for the faulty item.