How Should the Morning After Pill Be Taken

How should the morning after pill be taken?

A) two OCP each containing ethinyl oestradiol 50micrograms within 12 hours of sexual intercourse and two more taken at 72 hours post sexual intercourse
B) two such pills taken as a single dose within 72 hours of sexual intercourse
C) two such pills taken within 72 hours of sexual intercourse and two more taken twelve hours later
D) two pills taken at twelve hours post sexual intercourse and two more taken 72 hours later
E) two pills taken with 12 hours of sexual intercourse does not require a second dose