Fact 1: Viruses are so small that they can be seen only with an electron microscope. Fact 2: Electron microscopes are needed to see viruses. Given the two facts above, what can viruses be seen with?
OPT:
a). eye.
b). A computer.
c). magnifying glass.
d). microscope.
e). the skin.
f). radiation.
g). Chemical energy.
h). glasses.
Answer:
d).