The major link between the brain and the glandular system is the

The answer is the hypothalamus.

The hypothalamus is a small region of the brain. It’s located at the base of the brain, near the pituitary gland.  

While it’s very small, the hypothalamus plays a crucial role in many important functions, including: releasing hormones,  regulating body temperature,  maintaining daily physiological cycles,  controlling appetite,  managing of sexual behavior and  regulating emotional responses.

the correct answer, according to e2020, is the second choice there is an occluded front in region a and a cold front in region b.