Catabolism of protein is not a practical source of quick energy because of all of the following except that

A) proteins are more difficult to break apart than lipids or carbohydrates.
B) the energy yield from protein is less than the yield from lipids.
C) one of the by-products of protein catabolism is ammonia.
D) most individuals have little protein to spare before harming vital organs.
E) extensive catabolism of protein threatens homeostasis.