The pituitary gland is often called the "master of the endocrine system" because

A) it secretes eight different hormones that in turn regulate many of the other endocrine glands.
B) all other hormones must be activated by enzymes released by the pituitary gland.
C) it contains neuroendocrine cells that activate many of the other endocrine glands.
D) all blood vessels must pass through the pituitary so hormones can be regulated.
E) releasing and inhibiting factors for most other endocrine glands are released by the pituitary.