John Stuart Mill Says That Humans by Nature Desire Happiness

Multiple Choice

John Stuart Mill says that humans by nature desire happiness and nothing but happiness; therefore happiness is the standard by which we should judge human conduct, and therefore the principle of utility is at the heart of morality. But this argument is controversial, because

A) it reasons from what is to what should be.
B) it equivocates on the word "happiness."
C) it is internally inconsistent.
D) Mill failed to defend his theory.