Final answer:
The most common adverse effect a patient can expect when starting enteral nutritional supplements is diarrhea option (c), which can sometimes lead to dehydration and malabsorption syndrome.
Step-by-step explanation:
A patient who is just starting to take enteral nutritional supplements will be taught by the nurse to expect diarrhea option (c) as the most common adverse effect. Starting a regimen of enteral nutrition can lead to various digestive system reactions, such as nausea, stomach cramps, gas, and occasionally greasy stools. In some cases, if the diarrhea is severe, it may also lead to dehydration and sometimes to a malabsorption syndrome. Understanding and managing these symptoms are crucial in maintaining patient comfort and ensuring the efficacy of the nutritional therapy.