Which of the following foodborne illness symptoms involves gastrointestinal distress?

Diarrhea is a primary symptom of gastrointestinal distress. When foodborne illnesses occur, they often lead to inflammation of the stomach and intestines, also known as gastroenteritis. This condition is frequently accompanied by diarrhea as the body attempts to clear out the harmful pathogens, toxins, or irritants that may be present in contaminated food or water. The production of excess fluids in the intestines, in response to the infection or irritation, results in loose or watery stools, which characterizes diarrhea.

Muscle soreness, fatigue, and rashes, while they may occur in some cases of foodborne illness, are not direct symptoms of gastrointestinal distress. Muscle soreness can be related to illness but does not indicate a problem specifically within the digestive system. Similarly, fatigue is a general symptom of many illnesses and does not exclusively relate to gastrointestinal issues. Rashes are typically associated with allergic reactions or infections of the skin, rather than digestive problems. Therefore, diarrhea is the most relevant symptom linked to gastrointestinal distress among the listed options.