A prophage is a(n) __________.

• A. emerging virus
• B. virus that infects other viruses
• C. type of retrovirus
• D. prion that has been integrated into a bacterial cell's chromosome
• E. viral genome that has been incorporated into a bacterial cell's chromosome

Answer: (E)

Verified step by step guidance

1. Understand the context: A prophage is related to bacteriophages, which are viruses that infect bacteria.
2. Recognize that a prophage is a stage in the life cycle of a bacteriophage, specifically during the lysogenic cycle.
3. In the lysogenic cycle, the viral DNA is integrated into the host bacterium's chromosome, becoming a prophage.
4. The prophage can remain dormant within the bacterial genome until certain conditions trigger its activation.
5. Thus, a prophage is best described as a viral genome that has been incorporated into a bacterial cell's chromosome.