Viral DNA that inserts into a host genome.

• A. Bacteriophage
• B. Provirus
• C. Mycelium
• D. Hyphae

Answer: (B)

Viral DNA that inserts into a host genome is described as a provirus. This term refers to viral genetic material that becomes integrated into the host's chromosomal DNA and is replicated with every cell division. For retroviruses, the RNA genome is reverse-transcribed into DNA and then inserted into the host genome by the viral integrase, allowing the viral genes to be expressed later or to remain latent. Because the integration into the host genome is a defining feature here, provirus is the best fit for describing this situation.

A bacteriophage, while it can integrate its DNA into bacterial DNA, is specific to bacteria and the integrated form is called a prophage. The other two options, mycelium and hyphae, are related to fungal growth and have nothing to do with viral DNA integrating into genomes.