You are presented with the quiz "The expulsion of semen occurs when what propels sperm from the epididymes?" 

But you don't know the answer, so you turn to your teacher to ask for hints. He says that "ejaculation occurs when muscle contractions propel sperm from the epididymes" and "ejaculation is the expulsion of semen". 

So, what's the best answer to the question?


 

  muscle contractions         