Answer: B. Epididymis
Step-by-step explanation:
The region that'll be affected by the smooth muscle stimulant to help food move forward by peristalsis and hence leads to increased urination include the ductus deferens, urinary bladder and the urethra.
It should be noted that the epididymis isn't affected by the stimulant. The epididymis is simply the long, coiled tube which helps in the storage of sperm and then transports it from the testes.
The head of the epididymis is characterized by a thick epithelium which has a long stereocilia and a little smooth muscle. Therefore, the smooth muscle stimulant will not be necessary.