Select the description that would represent a pathogen that would be considered a virus.

a.

genetic material that is surrounded by a protein coat and uses a host cell to reproduce

b.

a single-celled organism that infects animals and plants

c.

an organism that feeds off others in order to gain its nutrients

d.

a single-celled organism that can be a parasite

The correct answer is option A.

Explanation:

Viruses refer to the microscopic, non-cellular infectious agents, which can only reproduce within the host cell. Viruses cannot be categorized as living or non-living. The viruses are dormant when they are present external of the host cells, however, turns active when present within the host cells.  

The viruses are enveloped by a protein coat, known as capsid and possess a core of nucleic acid constituting either RNA or DNA. A virus does not possesses the tendency to reproduce outside the host cell, as they are devoid of the needed cellular machinery. Thus, it invades and combines itself with a particular host cell, administers its genetic substance, and proliferates by utilizing the genetic substance of the host, and thus, create new viruses within the host.