Answer:
Option B. Viral genes may be encoded by DNA or RNA, but cellular genes are always encoded by DNA.
Explanation:
Virus is a unique organism having unique characteristics which act as both living and non living. In cell, it is living while outside the cell it is present in crystalline form. Virus is composed of two genome i. e. DNA or RNA. But cell is composed of only DNA genome. There is no nucleus present in virus. Mitochondria and ribosome are also absent.