Select the correct domain for each description.

Organisms in this domain can be unicellular or multicellular.

Organisms in this domain are unicellular and are often found in extreme environments.

Organisms in this domain have cells that contain a nucleus.

The correct domain for each description is as follows:

- Domain: Eukarya
- Domain: Archaea
- Domain: Eukarya

1. The correct domain for organisms that can be unicellular or multicellular is Eukarya.

2. The correct domain for unicellular organisms often found in extreme environments is Archaea.
3. The correct domain for organisms with cells that contain a nucleus is Eukarya.

The correct domains for each description are as follows:

1. Organisms in this domain can be unicellular or multicellular.
- The correct domain for this description is Eukarya. This domain includes organisms that can be both unicellular (such as protists) and multicellular (such as plants, animals, and fungi).

2. Organisms in this domain are unicellular and are often found in extreme environments.
- The correct domain for this description is Archaea. This domain consists of unicellular organisms that are often found in extreme environments such as hot springs, salt flats, and deep-sea hydrothermal vents.

3. Organisms in this domain have cells that contain a nucleus.
- The correct domain for this description is Eukarya. Organisms in this domain have eukaryotic cells, which means their cells have a distinct nucleus enclosed within a membrane. This domain includes all complex organisms such as plants, animals, fungi, and protists.