Norovirus is commonly associated with which of the following sources?

Norovirus is a highly contagious virus that is primarily linked to foodborne illnesses, particularly through contaminated shellfish. Shellfish, especially oysters, can accumulate the virus from contaminated water in which they are grown. When consumed raw or undercooked, these shellfish can transmit norovirus effectively to humans, leading to outbreaks, especially in settings such as restaurants and cruise ships where people are in close quarters.

The other options are generally associated with different foodborne pathogens. Raw meat is more commonly associated with bacteria like Salmonella or E. coli, while unpasteurized milk often carries pathogens such as Listeria or Campylobacter. Packaged snacks typically have a lower risk of containing harmful pathogens like norovirus unless they have been contaminated after production. Thus, contaminated shellfish is specifically and consistently recognized as a primary vehicle for norovirus transmission.