After many customers complained of nausea, diarrhea, and abdominal cramps, investigating authorities determined they had contracted Norovirus Gastroenteritis from eating contaminated stew. What could be two possible reasons for the contamination?

An infected food handler prepped the stew.
Meat from a torn packet can was used to prepare the stew.
The bread that was served with the stew had mold on it.
The stew contained contaminated shellfish.
The vegetables for the stew were washed carelessly.