Final answer:
The middle layer of the uterus is called the myometrium, which is made up of smooth muscle tissue and allows for powerful contractions during childbirth. Hence the correct answer is option B
Step-by-step explanation:
The middle layer of the uterus is called the myometrium. It is a thick layer made up of smooth muscle tissue that allows for powerful contractions of the uterus during childbirth.
Hence the correct answer is option B