This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Communicable diseases, Subject name: Social & Preventive Medicine
Commonest trophozite infection by sexual intercourse - 
Select and explain. 
A. Entamoeba histolytica, B. Trichomonas vaginalis, C. Trepanoma palidium, D. Giabrdia intestinales
B: Trichomonas vaginalis
Answer: B: Trichomonas vaginalis 
Explanation: Trichomoniasis has an estimated annual incidence of 173 million cases(Ref.PARK'S TEXTBOOK OF PREVENTIVE AND SOCIAL MEDICINE 21st Edition page no.304)