A microbiologist analyzes chemicals obtained from an enveloped RNA virus that infects monkeys. He finds that the viral envelope contains a protein characteristic of monkey cells. Which of the following is the most likely explanation?

• A. The virus forced the monkey cell to make proteins for its envelope.
• B. The virus is a prophage.
• C. Its presence is a result of the monkey's immunological response.
• D. The virus fools its host by mimicking its proteins.
• E. The viral envelope forms as the virus leaves the host cell.