D The term virus describes pathogens that are - a. not living Ob. bacteria c. living d. D cells

## Step 1<br />The term "virus" refers to a type of pathogen that is not considered living. This is because viruses lack the cellular structure and metabolic processes that are characteristic of living organisms. They cannot reproduce on their own and require a host cell to replicate. This distinguishes them from bacteria, which are living organisms, and from cells, which are the basic structural and functional units of life.<br /><br />## Step 2<br />The options provided question can be analyzed as follows:<br />a. "not living" - This is the correct description of viruses. They are considered non-living entities that can only replicate inside the cells of a host organism.<br />b. "bacteria" - Bacteria are living organisms and are not viruses. They are single-celled microorganisms.<br />c. "living" - This is incorrect as viruses are not considered living.<br /> "cells" - Cells are the basic structural and functional units of life and are not viruses.<br /><br />## Step 3<br />Therefore, the correct answer is option a, "not living".