The correct answer is option C, that is, viruses.
An infection occurs when a foreign species moves inside the body of an individual and causes harm. The species utilizes the body of that person to reproduce, sustain itself, and colonize. These infectious species are called pathogens. The examples of pathogens are viruses, bacteria, prions, and fungi.
Of the given options, viruses are the smallest infectious agent. The viruses are basic particles, which must infect a host cell to reproduce and develop. Viruses utilize the host cells metabolic machinery to double themselves.
Under the commercial name Orazine, Chlopromazine was introduced in the 1950s after a paradigm shift (extremely significant) or change from psychiatrists. Prior to this era, psychiatrists, as whole, did not readily recognize and therefore often improperly treated those with mental disorders.
Negative selection (D) removes the harmful alleles.
