Final answer:
The hypodermis is the layer of skin that acts as an energy reserve by storing adipocytes and releasing them into circulation when energy is needed. Thus, the option c is the correct answer.
Step-by-step explanation:
The hypodermis, also known as the subcutaneous tissue, is the layer of skin that acts as an energy reserve by storing adipocytes (fat cells) and releasing them into circulation when energy is needed. Adipose tissue present in the hypodermis consists of fat-storing cells called adipocytes. This stored fat can serve as an energy reserve, insulate the body to prevent heat loss, and act as a cushion to protect underlying structures from trauma.