Which part of a feedback mechanism is able to monitor the conditions outside of cells and usually uses nerve cells to relay this information to an integrating center?
a.) sensor
b.) effector
c.) stimulus
d.) response

A.) sensor

Explanation:

Homeostasis is the ability of the organism's inner body to regulate the internal environment in stable state with respect to the changes occurring in the external environment. It is usually done by the feedback controls.  

The maintenance of homeostasis within the body is essential. The following are the factors which controls the homeostasis. These includes:

1. Stimulus: It generate a response. It is an external factor which brings change in the internal body of the organism.

2. Receptor/ sensor: It detects the external stimulus and responds to the change.

3. Control center: The information from the receptor travels along the afferent pathway towards the control center. The function of the control center is to determine the response and controls the action.

4. Effector: The information from the control center travels down the efferent pathway to the effector. The function of the effector is to balance the stimulus to regulate and maintain homeostasis.

e) none of the above answers are correct