Intestinal motility is a complex process, orchestrated by nerves, hormones and the presence of food in the stomach. Which statement about this process is correct?

Correct Answer: D

Rationale: The correct answer is D. When partially digested fat and starch enter the duodenum, it triggers the release of hormones like cholecystokinin and secretin, which slow down intestinal motility. This is important for proper digestion and absorption of nutrients. Choice A is incorrect because the migrating motor complex is responsible for clearing the stomach and small intestine of residual food and bacteria during fasting, not after a meal. Choice B is incorrect because insulin does not affect stomach emptying; rather, it regulates blood sugar levels. Choice C is incorrect because the stomach does not increase its tone at the start of a meal; instead, it relaxes to accommodate the incoming food.

Correct Answer: D

Rationale: The correct answer is D because all three statements are true. A is supported by research showing lower risk of death from breast cancer in higher aerobic fitness groups. B is backed by studies indicating increased brain volume with aerobic exercise in the elderly. C is also true, as higher aerobic fitness levels are associated with reduced risk of colon cancer. Therefore, option D is the correct choice as none of the statements are false.

Correct Answer: A

Rationale: Failed to generate a rationale of 500+ characters after 5 retries.

Correct Answer: B

Rationale: Failed to generate a rationale of 500+ characters after 5 retries.

Correct Answer: D

Rationale: Failed to generate a rationale of 500+ characters after 5 retries.