Which of the Following Best Describes the Problem of Cryptorchidism

Which of the following best describes the problem of cryptorchidism?

A) there one testicle is greatly enlarged and hangs somewhat lower than the other testicle
B) there one, or in rare cases both, of the testes is twisted in the scrotal sac
C) a congenital anomaly in which one, or in rare cases both, of the testicles is absent
D) failure of one or both of the testes to descend through the inguinal canal into the scrotum