The hypothalamus acts as what aspect of many homeostatic feedback loops? A. Hormone
B. Controller
C. Sensor
D. Effector

I think the answer is C

Explanation:

the hypothalamus has a Negative Feedback Loop: The hypothalamus secretes corticotropin-releasing hormone. So I'm pretty sure the answer is  a sensor because it regulates the temperature of the body and energy maintenance, and in the process of memorizing and in stress control. It also modulates the endocrine system through its connections with the pituitary gland.

I hope this helps but i'm not 100% sure

answer; polycythemia is the correct answer;