Final answer:
Increased osmolarity in the duodenum would result in increased water diffusion into the small intestine and distention of the small intestine, but would not necessarily cause increased activation of pepsinogen. Decreased HCl secretion in the stomach is the option that would not occur in response to increased osmolarity in the duodenum. The answer is option C.
Step-by-step explanation:
The question asks about the effects of an increase in the osmolarity of the contents of the duodenum. Increased osmolarity in the duodenum would indeed lead to an increased diffusion of water into the small intestine to balance the osmotic pressure, resulting in the distention of the small intestine. This is due to water moving from an area of lower solute concentration (blood and interstitial fluid) to an area of higher solute concentration (intestinal lumen with increased osmolarity).
Activation of pepsinogen, an enzyme precursor activated by stomach acid, into active pepsin occurs in the stomach and is related to the acidic environment and not directly influenced by the osmolarity of the duodenum. Therefore, option 'c. increased activation of pepsinogen' would not necessarily occur due to an increase in the osmolarity of the duodenum contents. Instead, the decreased HCl secretion in the stomach would be the correct answer as it would not be an expected response to increased osmolarity in the duodenum.