Which of the following occurs in the expulsion stage of ejaculation in men?

A) The bladder's sphincter muscle closes to prevent urine from mixing with the semen and semen from entering the bladder.
B) There are rapid, rhythmic contractions of the urethra, the prostate, and the muscles at the base of the penis.
C) Men feel a highly distinct sensation of ejaculatory inevitability.
D) A sphincter below the prostate closes to trap semen in the expanded urethral bulb.

During the expulsion stage of ejaculation, there are rapid, rhythmic contractions of the urethra, the prostate, and the muscles at the base of the penis, which help propel semen out of the body. A, C, and D are all events that occur during other stages of ejaculation. The closure of the bladder's sphincter muscle to prevent urine from mixing with semen and semen from entering the bladder occurs during the excitement stage. The highly distinct sensation of ejaculatory inevitability is a hallmark of the orgasm stage. And the closure of the sphincter below the prostate to trap semen in the expanded urethral bulb happens during the emission stage.