Answer: a. runs through the infundibulum
Explanation: The hypothalamus and the pituitary gland (hypophysis) are linked by a structure called the infundibulum. The infundibulum contains vasculature and nerve axons, these nerve axons have endocrine properties.
The hypothalamic-hypophyseal tract runs through this infundibulum
PCR technique is your answer
Only 10% is gained going up the chain