Biology

The correct answer is: A.Archaea.

Here’s why:

1.Unicellular organisms with no nuclei: Both Archaea and Eubacteria are prokaryotic, meaning they lack a true nucleus. However, Archaea are more specifically known for their ability to survive in extreme environments.

2.Living in the superheated waters of a hot spring: Archaea are famous for thriving in extreme environments such as hot springs, deep-sea vents, and other places with high heat, acidity, or salinity. These organisms are called extremophiles, and they are often found in conditions that would be inhospitable to most other forms of life.

Now, let's break down the other options:

B.E...