Under GAAP, an entry should be made to the bad debt expense account
a. When an account receivable with terms 2/10, n30 is past thirty days due.
b. When an account receivable previously written off is determined to be collectible
c. When an account receivable is determined not to be collectible and is written off
d. In the period when a sale is made and not when the receivable associated with the sale is determined to be uncollectible.