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

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

Answer:
The probable reason is that the chaat was contaminated by pathogenic microbes clue to unhygienic conditions near the shop or the utensil used for serving could have contaminated.