Fact 1: TRH stimulates the pituitary gland to produce thyroid-stimulating hormone, or TSH.

Fact 2: Another function of TSH is to maintain the structural integrity of the thyroid gland.

Given the two facts above, answer the question "What stimulates the pituitary gland in order to maintain structural integrity of the thyroid?" with the following options: 
- TRH
 - Urea
 - CO 2
 - PDAs
 - HPV
 - SO2
 - mL
 - p53


 

 TRH        