Which Explanation Is One of the Reasons for the Ability

Which explanation is one of the reasons for the ability of the influenza virus to evolve rapidly?

A) Its single-stranded DNA genome is sensitive to environmental factors that create mutations.
B) The enzyme that replicates its RNA genome is prone to make mistakes that result in mutations.
C) Its ability to integrate into the host genome allows it to remain in host cells for long periods of time.
D) It can convert its RNA genome into a DNA copy by using the enzyme reverse transcriptase.
E) It has the ability to replicate its genome both within the host cell and outside of it.