A Friend of Yours,as a Biology Major,has Prepared Microscope Specimens

A friend of yours,as a biology major,has prepared microscope specimens from a rat that had been found dead for unknown reasons.Viewing the prepared slide with a light microscope,your friend points out many small round objects,each about 1/10th the diameter of the nearby rat cells,identifying those round objects as viruses,the likely reason for the rat's death.You can interpret from the observations that

A) the viruses your friend identified were likely received as an infection from another organism.
B) these are more likely bacteria, being too large for viruses.
C) they are indeed viruses, likely received from another organism, and are also specifically common bacteriophages.
D) they are probably specialized bacteriophages that commonly infect mammals.
E) they are capsids, which have evolved as a transition between viruses and bacteria.