The FDA's Pregnancy Safety Designation of Category a for a Drug

The FDA's pregnancy safety designation of Category A for a drug means :

A) no adequate animal studies or adequate studies of pregnant women have been done.
B) animal studies have demonstrated adverse effects, but there are no adequate studies in pregnant women; benefits may be acceptable despite the potential risks.
C) adequate studies in pregnant women have not demonstrated a risk to the fetus in the first trimester or later trimesters.
D) fetal risk has been demonstrated, which outweighs any possible benefit to the mother; avoid using in pregnant or potentially pregnant patients.