a virus suspended in the air an accident on a playground a genetic mutation in somatic cells an occurrence of acid rain
I am hesitating between 4 options to answer the following question, which option should I choose?
Question: What condition is most likely to spread an illness between people?
Possibilities:
- a virus suspended in the air
- an accident on a playground
- a genetic mutation in somatic cells
- an occurrence of acid rain

a virus suspended in the air