The correct option is B small intestine, sphincter muscle
The alimentary canal in the human digestive system continues from the stomach into the small intestine. Food stays in the stomach for around 3 hours where it is slowly churned into a more slimy mix called chyme. The chyme is slowly released into the duodenum of the small intestine at regular intervals for further digestion by the action of pancreatic and bile juices. The release of chyme is controlled by a set of circular ring-like muscles known as sphincter muscles. Such circular muscles are present at multiple places in the alimentary canal and control the movement of the digesting food mass.