Answer:
B. a tripod
Step-by-step explanation:
We cannot have any problem with the electronic viewfinder, because is part of the camera, with this viewfinder we can see the picture that we will take.
A camera lens can be huge or tiny, but we cannot hurt anyone with them, and headphones are harmless.
In this example we have a tripod, there are different types of tripods, but always have three legs, and we could hurt someone if we don't carry it properly.