While returning from the school. Boojho ate chaat from a street hawker. When he reached home, he felt ill and complained of stomach ache and fell ill. What could be the reason?

The reason could be the chaat might have been contaminated with pathogens due to unhygienic conditions near the chaat shop or utensils in which chaat was served.

If the food is left uncovered the flies might sit on the food and spreads disease-causing pathogens, so when Boojho ate that contaminated food he felt ill and complains of a stomach ache.