Question

select the best evidence to support the statement that dolphins use their blowholes for breathing.
dolphins and porpoises are whales, or cetaceans (the scientific name for whales). dolphins and porpoises are smaller, toothed whales. larger whales such as the blue whale have a comblike strainer made of baleen, or whalebone, in their mouths instead of teeth...
all whales are mammals. that means that they are warm - blooded, have babies that are born alive and feed on milk, and have hair or fur on some part of their bodies. whales live in water but have lungs. when they come to the surface, they breathe air through an opening on top of their heads called a blowhole. when a whale surfaces, it spouts a \blow\ of water vapor.
from seymour simon, dolphins. copyright 2009 by seymour simon

Explanation:

The text clearly states that whales (including dolphins as they are cetaceans) live in water but have lungs. When they come to the surface, they breathe air through the blowhole on top of their heads. This directly links the blowhole to the act of breathing.

Answer:

When they come to the surface, they breathe air through an opening on top of their heads called a blowhole.