Read the following description. Clusters of cells located near the carotid artery in the neck sense the amount of oxygen in the blood. If the level is too low, these arteries send signals to the brain that result in an increased breathing rate, which increases the amount of oxygen in the blood.

This is an example of which of the following?

positive feedback helping to maintain homeostasis
positive feedback to amplify small signals
negative feedback to amplify small signals
negative feedback helping to maintain homeostasis