Task: Question Generation
Input (English): Background Paragraph: Some processes in the body are regulated by positive feedback. Positive feedback is when a response to an event increases the likelihood of the event to continue. An example of positive feedback is milk production in nursing mothers. As the baby drinks her mother's milk, the hormone prolactin, a chemical signal, is released. The more the baby suckles, the more prolactin is released, which causes more milk to be produced. Other examples of positive feedback include contractions during childbirth. When constrictions in the uterus push a baby into the birth canal, additional contractions occur. 
Story: John is a doctor at the children's hospital. He had two different cases to investigate, case A and case B. In case case A, a baby continued to suckle mother's milk. But in case B, a baby stopped suckling mother's milk. He had to determine the different effects these two cases were causing.
Output (English): Which is not an example of positive feedback, case A or case B?