Answer:
B. No effect on net income; no effect on total assets
Explanation:
When you write off bad debt, the journal entry is:
Dr Allowance for doubtful accounts XYZ
Cr Accounts receivable XYZ
This actually had no effect on the income statement, since the allowance account is already a contra asset account.
When the write off is reversed because the customer paid the debt, the journal entry is:
Dr Accounts receivable XYZ
Cr Allowance for doubtful accounts XYZ
Dr Cash XYZ
Cr Accounts receivable XYZ
Again, since the company is using the allowance method, there is no real effect on the income statement nor total assets in the balance sheet.