Final answer:
The range of host cells a virus can infect is called its host range, and it is determined by the specific interaction between the virus and the host cell's receptors. So the correct option is C.
Step-by-step explanation:
The range of host cells that a virus can infect is called its host range. This term refers to the particular species and cell types a virus is capable of infecting. Most viruses have a limited host range, meaning they can only infect the cells of one or just a few species of organisms. For example, viruses that infect bacteria are known as bacteriophages or phages. The specificity of a virus for its host is largely due to the interaction between viral attachment proteins and specific receptor sites on the cell membrane of the potential host.