Correct Option: B

Influenza virus is a retrovirus wherein, the genetic material comprises of RNA. There are three genera of influenza virus, identified by antigenic differences in their nucleoprotein and matrix protein:
• Influenza virus A are the cause of all flu pandemics and are known to infect humans, other mammals and birds (see also avian influenza).
• Influenza virus B are known to infect humans and seals.
• Influenza virus C are known to infect humans and pigs.