Respuesta :
Viruses because children immune system cannot repeal parasites (no one can) or bacteria that is why we wash or hands. Fungi is not something we can repeal either.
Answer:A - viruses
Explanation:
Children immune system is comparitively weeker than the adult immune system.
Thus children are more susceptible to acquire viral infection which exhibit a parasitic prolonged infection. Children are more susceptible to cold and flue virus than adults due to lack of immunity.