If a writer wants to write about the subject/topic of, "dolphins", what could be a main idea of their passage?

Question

Responses

The ocean has many different habitats.
The ocean has many different habitats.

Dolphins can be found in a variety of locations around the world.
Dolphins can be found in a variety of locations around the world.

Sharks are predators that consume a lot of different types of sea creatures.
Sharks are predators that consume a lot of different types of sea creatures.

Ecosystems are important to conserving wildlife.

Answer 1

Dolphins are fascinating and intelligent creatures that play an important role in ocean ecosystems.