The most common site for amoebiasis is:

The correct option is Cecum.

Amoebiasis is an infectious disease caused by the protozoan parasite Entamoeba histolytica. It primarily affects the human gastrointestinal tract. After ingestion of viable cysts from contaminated food or water, excystation occurs in the small intestine, releasing active trophozoites that migrate to the large intestine.

Within the large bowel, the parasite tends to localize in regions where the transit of intestinal contents is slowest. The cecum and the ascending colon are the areas of maximum stasis. Consequently, the cecum is the most common site of colonization, tissue invasion, and primary pathology in amoebic colitis. Other sites in the colon, such as the sigmoid colon, transverse colon, and hepatic flexure, can also be involved, but they are less frequently affected than the cecum.