If Alpha is using accrual accounting, when does it record the revenue for this sale?

The Alpha company ships an order to a customer on March 1st and invoices the customer for the product with the shipment, with payment terms of net 30 days. The customer’s payment is received on April 5th. The payment clears the bank and shows on Alpha’s account on April 8th.

If Alpha is using accrual accounting, when does it record the revenue for this sale?
A . March 1st
B . March 31st
C . April 5th
D . April 8th

Answer: A