Polyhedral virusesX Helical virusesEnveloped virusesComplex viruses have an outer lipid bilayer known as a viral envelope, which is studded with proteins. Influenza and HIV are examples.

Enveloped viruses have an outer lipid bilayer called a viral envelope, often studded with proteins that help the virus attach to host cells. Influenza and HIV are examples, so the correct choice is Enveloped viruses.

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