Using the Allowance Method for Bad Debts Expense,the Allowance for Doubtful

Using the allowance method for bad debts expense,the Allowance for Doubtful Accounts is decreased:

A) When the estimate of bad debts is expensed.
B) When a specific customer account is written off.
C) When a specific customer account is collected.
D) When a sale to a credit customer is made.
E) When all customer accounts are considered collectible.