Clue: If you can add "and" and it sounds correct, you need a comma. Choose the sentence in which the adjectives are punctuated correctly.
A. We heard four, sharp trumpet blasts signal the entrance of the royal visitors.
В.
We heard four sharp, trumpet blasts signal the entrance of the royal visitors.
O C. We heard four sharp trumpet blasts signal the entrance of the royal visitors.
D. We heard four, sharp, trumpet blasts signal the entrance of the royal visitors.