<prompt> A 4 year old child presents with acute watery diarrhea and abdominal cramps. Stool microscopy reveals trophozoites with falling leaf motility. The etiological agent is?Entamoeba hisioluticsGiardia lambliaTrichomonas tenaxBalantidium coli  <response>: The trophozoite is motile, with a slow oscillation about its long axis, which has been likened to the motion of a falling leaf. It divides by longitudinal binary fission. It lives in the duodenum and upper pa of the jejunum attached by means of the sucking disc to the epithelial cells of the villi and crypts feeding by pinocytosis 