RNA is genetic material in
a. ${T_2}$ virus
b. ${T_4}$ virus
c. SV-400
d. TMV

Hint: Ribonucleic acid (RNA) is a polymeric molecule used in various biological roles in an organism like coding, regulation, decoding and expression of genes. Both DNA and RNA are nucleic acids and assembled as chains of nucleotides, but RNA is found in nature as a single strand folded into itself rather than paired double strands like DNA.

Complete answer:
RNA is a single strand chain of nucleotides and is present in some viruses. Tobacco mosaic virus (TMV) is a positive single stranded RNA virus species in the virus genus Tobamovirus that affects a wide range of plants especially tobacco plants from which it gets this name. This virus also affects the other members of family Solanaceae, This virus affects the plants and causes characteristic patterns such as mosaic like mottling and discoloration of the leaves. TMV is also the first virus to be discovered in the late 19th century in which it was damaging the tobacco crops. The RNA molecules present in the TMV virus as the genetic material.

Tobacco mosaic virus is a rod-like virus that has a capsid made from 2130 molecules of the coat protein and one molecule of genomic single stranded RNA which is 6400 bases long. The coat protein self-assembles into rod-like helical structure around the RNA which forms a hairpin loop structure.

Hence, the correct answer is option (D).

Note: The RNA present in the TMV is a positive single stranded RNA virus that infects all around of plants. The genome of the TMV virus consists of 6.3 to 6.5 kb single stranded RNA. The 3-terminus has tRNA like structure and the 5- terminus has a methylated nucleotide cap.