What type of agents would be used for symptomatic relief of diarrhea?

The correct choice for symptomatic relief of diarrhea is antidiarrheals. These agents work by slowing down bowel movements, which decreases the number of stools and makes them less watery. Antidiarrheals can help manage the symptoms associated with acute diarrhea rather than addressing the underlying cause of the diarrhea itself.

Laxatives, in contrast, are used to promote bowel movements and are contraindicated in cases of diarrhea since they can worsen the condition. Mast cell stabilizers are primarily used in treating conditions like asthma and allergic responses but do not have an effect on diarrhea. Smoking cessation agents are designed to help individuals quit smoking and have no relevance to managing gastrointestinal symptoms. Thus, antidiarrheals are the appropriate choice for providing symptomatic relief in cases of diarrhea.