Chemical digestion in the small intestine involves a. a significant amount of enzyme secretion by the intestinal mucosa b. cholecystokinin (cck), an intestinal hormone responsible for gallbladder contraction c. secretions from the spleen that contain all enzymes necessary for complete digestion d. bile salts that emulsify carbohydrates so that they can be easily digested by enzymatic action

b.cholecystokinin (CCK), an intestinal hormone responsible for gallbladder contraction

Explanation:

Chemical digestion is the process that involves the breakdown of chemical bond that holds food particles together into small parts to nourish the cells in the body. Thus, almost all chemical digestion takes place in the small intestine and enzymes used for the purpose of digestion are usually secreted by the pancreas which enters the small intestine through pancreatic duct. Furthermore, the entrance of digestive enzymes into the small intestine can only occur only when cholecystokinin hormone is secreted which is responsible for digestion of fats and protein.

the oxygenated blood then leaves the lungs through pulmonary veins, which return it to the left heart, completing the pulmonary cycle. this blood then enters the left atrium, which pumps it through the mitral valve into the left ventricle. from the left ventricle, the blood passes through the aortic valve to the aorta.

deoxygenated blood leaves through the right ventricle through the pulmonary artery. from the right atrium, the blood is pumped through the tricuspid valve (or right atrioventricular valve), into the right ventricle.