Question

the viral structure responsible for recognizing specific host cells is - a retrovirus. genetic material. a surface protein. a bacteriophage.

Explanation:

Viruses use surface proteins to bind to specific receptors on host cells. Retroviruses are a type of virus, genetic material (like DNA/RNA) carries the virus's genetic information, and bacteriophages are viruses that infect bacteria. But the structure for host - cell recognition is the surface protein.

Answer:

C. a surface protein.