I never understand these questions so let’s just look at them logically
Leaving the room: Makes enough sense, in the event that the “accident” is lethal, you don’t really want to be there.
Calling the paramedics: I feel like this is an overreaction, the “accident” might not even be serious
Locate the first aid kit: Also in the same vein as paramedics, what are the chances that the accident causes harm
Call a teacher: They should know what to do, or at least, they’re the “adults”, so that’s probably your best bet