I wish someone could help me with this basic account question please.

Answer ALL FOUR Questions April, Grinnel Paving Limited acquired a large quantity of crushed stone on account with payment due in 90 days. The stone was used in May when Grinnel Paving Limited completed a large parking lot for a local shopping center. In early July, Grinnel Paving Limited paid the supplier from which the crushed stone had been obtained. In which month should Grinnel Paving Limited recognize the cost of the crushed stone as an expense? What accounting principle provides the justification for the answer? (15 points) 1. In Answer of Q1