During a physical activity, what hormone signals the fat cells to begin releasing their fatty acids?

The hormone being referred to is Epinephrine. 
This hormone is secreted mainly in the medulla of the adrenal glands and it functions primarily to increase cardiac output and to raise glucose levels in blood. Normally the hormone is produced during acute stress, and its stimulatory effects fortify and prepare individual for fight or flight.

Well i had the same answer, so the correct answer would be a. but in this case it would be the one with plasma membrane and cell wall circled that is next to the hairy pill type of thing.