Final answer:
The most important feature of the Influenza Virus is its envelope, which is composed of a lipid membrane and studded with spike proteins.
Step-by-step explanation:
The most important feature of the Influenza Virus is its envelope, which is composed of a lipid membrane and studded with protein spike proteins called hemagglutinin (H) and neuraminidase (N).
These spike proteins play critical roles in the viral infectious cycle, including attachment to host cells and release of new virions.