Answer: A is the best answer.
Explanation: Muscles are the tissues made up of actin and myosin proteins that helps in movement while fats make up the adipose tissue and stored fats will eventually utilize in the expenditure of energy during starvation. So these two are different and cannot be convertible in to one another. Same Calories taken in physical inactivity as in exercise leads to the loss of muscle's mass or strength results in shrinking of muscular tissues and excess calories will be stored as body fats in adipose tissue.