Viruses are so small that they can be seen only with an electron microscope, and once the camera is tuned with the microscope, the focusing depends on the microscope lens. Given these facts, viruses are so small that they can be seen by what among the following options:
- focusing a lens
 - A computer
 - looking close
 - rays or beams
 - sunlight
 - bending light rays
 - seeing smaller
 - tuning eyes


 

 focusing a lens        