Correct Option: A

All viruses are nucleoproteins (Nucleic acid + Protein) in the structure. The nucleic acid (DNA and RNA) is the genetic material. In a particular virus either DNA or RNA is the genetic material. Both are never present in a virus. Single stranded RNA or ss RNA - Tobacco mosaic virus (TMV) Virus envelope is known as capsid. The capsid is composed of protein subunits called capsomere.