A package labelled 4.3 is leaking onto a wet loading bay. What is the characteristic Class 4.3 hazard?

1. The substance is an organic peroxide that must be kept refrigerated at all times
2. The substance emits flammable gases in contact with water
3. The substance is only a marine pollutant and is harmless on land
4. The substance is a toxic gas already in Class 2.3