Final answer:
Option (A), Payroll tax deposits mailed using USPS are considered timely if they are postmarked at least one day before the due date, avoiding any penalties.
Step-by-step explanation:
When an employer mails payroll tax deposits using the US Postal Service, the deposits are generally considered timely if they are postmarked by the due date of the deposit. In most scenarios, as per the IRS guidelines, a deposit is timely if it is postmarked on or before the due date.
Specifically, the deposit should be postmarked by the U.S. Postal Service at least one day before the due date to be considered on time to avoid penalties. This would correspond to option A. One day.