D. The release of oxytocin in response to stretching of the uterus.
Explanation:
There are two types of feedback loops, negative and positive.
Negative feedback loops' main goal is to maintain homeostasis, or equilibrium within the body. When there is a stimulus, the negative feedback loop will try to make the output less than it is, to make homeostasis equal again. An example of this would be regulating blood sugar. If your blood sugar levels are low, your body will release glucagon to make them higher, that is a negative feedback loop.
Positive feedback loops' main goal is to make the reactions go by more quickly, it makes the equilibrium unstable while accelerating the reaction. An example of this would be releasing chemicals in the body such as oxytocin, during childbirth to make it less painful and to speed up the process.
