Which of the Following Is(are)advantages to the Constant Degradation and Reformation

Which of the following is(are) advantages to the constant degradation and reformation of proteins?

A) Nutrients can be stored as proteins,which can be used during periods of metabolic need.
B) Damaged proteins are eliminated so they do not accumulate.
C) Metabolism can be efficiently regulated by the synthesis and degradation of enzymes.
D) All of the above are advantages.
E) None of the above is an advantage.