Martin observes a wet mount slide preparation using the compound light microscope in the lab room. He observes layers of cells that have a definite, rigid, rectangular shape; there appears to be a nucleus in all of the cells and there are many oval-shaped green structures that seem to be moving around inside of the cells in an orderly fashion. What general cell type is he MOST likely observing?

A plant cell

Explanation:

In the given question, the characteristics of a cell are provided which includes:

1. Rectangular shaped cells which are rigid: Rigidity of a cell is provided by the cell wall which is a characteristic feature of the plant cell.

2. Possess a nucleus: which shows that the organism is a eukaryote

3. The oval-shaped green structures: the oval-shaped structure which can move is the chloroplast which provides the site for photosynthesis.

Thus, it is confirmed that the observed cell is of a plant cell.