Answer:
The billing function should be assigned to persons other than those responsible for maintaining accounts receivable subsidiary records.
Step-by-step explanation:
The first choice it's considered an effective Internal control procedure for accounts receivable.
This is because it is not safe that the person who prepares the billing is the same who record cash receipts or any other document over the account receivables.
This is what we call Segregation of Duties and this is an internal control determined to avoid fraud or error.