Final answer:
The correct statement is that cells have a nucleus, while viruses do not. Viruses are smaller than cells, lack membrane-bound organelles, and require a host to reproduce.
Step-by-step explanation:
When comparing the structure of a virus to a cell, it is important to identify the correct characteristics of each. The accurate statement from the options provided is: Cells have a nucleus, but viruses do not. Viruses are much smaller than cells and do not have membrane-bound organelles or a nucleus. They consist of genetic material, either DNA or RNA, encapsulated in a protein coat called a capsid. In some cases, they may also have an outer envelope which is acquired from the host cell. Unlike cells, they lack the machinery for self-replication and must infect a host cell to reproduce.