Which of the following is a characteristic by which viruses are classified?

a. type of nucleic acid

b. type of life cycle

c. number of chromosomes

d. type of host

e. size

Type of nucleic acid.

Explanation:

Virus may be defined as the organism that can contains both DNA and RNA as their genetic material. Virus acts as non-living outside the host environment and later acts as living organism inside the host.

Some virus that particularly contain DNA as genetic material. Some virus has the ability to transform RNA into the DNA molecule. Some virus contains only RNA as their genetic material and DNA is not involved in their life cycle.

Thus, the correct answer is option (a).