Asap. i also need explanations to go with the answer

D. In an ocean heated by volcanic activity

Explanation:

Most of Earth was covered in water, early organisms weren't evolved enough to walk on land at the time. There are some organisms that feed off of volcanic activity and use it as an energy resource and would adapt to the heat.

"Hot spots create volcanoes on the seafloor. If these volcanoes rise above sea level to become islands, and if they occur in tropical waters, coral reefs will form on them. Since the volcanoes are cones, the reef forms in a circle around the volcano."

-https://courses.lumenlearning.com/earthscience/chapter/ocean-organisms/

"Discovered only in 1977, hydrothermal vents are home to dozens of previously unknown species. Huge red-tipped tube worms, ghostly fish, strange shrimp with eyes on their backs and other unique species thrive in these extreme deep ocean ecosystems found near undersea volcanic chains."

-https://ocean.si.edu/ocean-life/invertebrates/hydrothermal-vent-creatures

the sea slugs belong to the same class