After a papercut, activated platelets release chemical signals to activate more platelets. In this example, the chemical signal is the of a feedback loop. a. Set point
b. Effector
c. Receptor
d. Metabolism

a. Set point

Explanation:

Homeostasis is the maintenance of internal body environment within a given range.

The set point is the range around which normal body environment should be. For example the set point for body temperature is 37°C. The body works to maintain temperatures around this value.

When a stimulus happens the sensory organs sends the final to the control center.

The control centre ascertains if condition is around the set point.

It then sends signals to the effector to restore balance.

So when platelets release chemical signals to activate more platelets, it is a set point feedback loop trying to restore normal conditions.

is the answer

explanation: