Which of the following best describes the viral genome?

• A. Always single-stranded RNA
• B. Either DNA or RNA, but never both
• C. Always double-stranded DNA
• D. Both DNA and RNA present simultaneously

Answer: (B)

Verified step by step guidance

1. Understand that viruses can have genomes made of nucleic acids, which carry their genetic information.
2. Recall that viral genomes can be composed of either DNA or RNA, but not both at the same time within a single virus particle.
3. Recognize that viral genomes vary in structure: they can be single-stranded or double-stranded, and can be RNA or DNA, depending on the virus type.
4. Eliminate options that state the genome is always single-stranded RNA or always double-stranded DNA, since viral genomes are more diverse than that.
5. Conclude that the best description is that viral genomes are either DNA or RNA, but never both simultaneously in the same virus.