When Does Failures in the Use of the Contraceptive Pill

Multiple Choice

When does failures in the use of the contraceptive pill usually occur?

A) When the pill does not contain enough estrogen.
B) When a woman switches brands and the new pill is not as effective as the one she had been on.
C) When a woman forgets to take the pill for a day or two or so.
D) When a woman has intercourse with a male who is highly fertile in the number of sperm he produces.