If the total on the schedule of accounts receivable and the Accounts Receivable balance in the general ledger do not agree, the error

a$.$ must be in the total of the schedule.

b$.$ must be in the controlling account in the general ledger.

c$.$ could be in the total of the schedule, the postings to the subsidiary ledger, or in the controlling account in the general ledger.

d$.$ must be in the postings to the subsidiary ledger.