I was wondering if you could help me with my accounting question?

1. Which of the following business events does not need a negative amount to record transaction?

a) A retail sale invoice for a pair of sunglasses was issued for 172.89 (153.00 plus tax) and should been issued for the correct amount of 152.55 (135.00 plus taxes).

b) Write off a customer balance due to the bankruptcy of the customer.

c) Record a sale with HST to a customer.

d) Record the return of an unopened USB drive by a customer.