Yes
To keep their species going.
only one species of dolphins at this time that are going extinct are the pink river dolpinsHector's dolphins (New Zealand dolphins) are also in danger of becoming extinct. The endangered river dolphins are Amazon River dolphins, Ganges River dolphins, Chinese White dolphins, Indus River dolphins, and La Plata River dolphins.
Maybe
no
If someone is going to be attacked by a shark, dolphins fight the shark
All dolphins are not going endangered. Only a few species are. The IUCN Redlist is an excellent resource for info on these species.
No
To keep their species going.
No
Well they certainly do not sell groceries! Dolphins live in pods (a group of dolphins) and carry offspring, keeping their species going in the world.
not yet, but soon
Yes