The most efficacious medication for treatment of the flagellated protozoan Trichomonas vaginalis in a nonpregnant, immunocompetent female patient is:
a) Metronidazole (Flagyl).
b) Doxycycline (Vibramycin).
c) Clindamycin (Cleocin).
d) Clotrimazole (Lotrimin).
