Most common cause of dysentery in adults is?

ANSWER: (D) EntamoebaREF: VariousThis was a difficult one and quite a nagging question, because no book gives a perfect answer.However after consulting various websites. CMDT, Harrison I reached the conclusion that most common cause of dysentery is bacterial > parasitic.Robbin's states that shighella is the prominent cause of dysentery in countries with poor hygiene, like India etc, while amongst parasites, it states that entameoba histolytica is major cause of dysentery.