The double-stranded viral DNA can be incorporated into the host T4 genome as a:

Explanation

A prophage is a phage DNA that has been integrated into the DNA of a bacterial host cell. This is a common phenomenon in bacterial viruses like the T4 bacteriophage. The viral DNA becomes a part of the host cell's genome and remains dormant within the host until certain conditions trigger its activation and subsequent replication, leading to the lytic cycle where new phage particles are produced and released.