When using the transdermal patch, which of the following techniques is correct?
A.It should be inserted into the vagina and left in place for 30 days.
B. It must be applied six hours before sex and left in place for 12 hours after sex.
C. A woman replaces the old patch with a new one on the same day each week for three weeks and then takes a patch-free week.
D. It is inserted under the skin, below the armpit.