The table lists the observations students made about four specimens under a microscope, based on these observations what specimens did the students examine ?
options - animal , plant , virus, and prokaryote

Animal cells have a cell membrane and not a cell wall. They have ribosomes and lysosomes and their nucleus is enveloped by a nuclear membrane. This means that the first description;

Cell membrane present;
ribosomes present;
lysosomes present;
nuclear membrane present.

Matches ANIMAL.

Plant cells on the other hand have something called a cell wall, which are more rigid than cell membranes. Plant cells are known for their large vacuole. They also have a nuclear membrane that covers its nucleus.
The third description:
Cell wall present
Ribosomes present
Nucleus present
Large vacuole present

Matches PLANT.

Viruses do not have any membrane on its wall nor its nucleus. Basically, they have no internal structures. The fourth and last description:

Reproduces inside of a cell
Nucleus absent
RNA present

Matches VIRUS

Prokaryotes are primitive cells and they do have a cell wall but they have no defined nucleus, which means they do not have a nuclear membrane. The second description:

Cell wall present
Ribosomes present
Nuclear membrane absent

Matches PROKARYOTE 

The answer is constant.