Would it be A?

What portion of the electromagnetic spectrum can human eyes detect?

A.

visible light

B.

visible light and infrared light

C.

infrared light

D.

infrared light and ultraviolet light

Well, there's a very definite reason why a certain sliver of the electromagnetic

spectrum is called "visible".

The meaning of the word 'visible' is 'can be seen with eyes', and that's the label

given to the part of the electromagnetic spectrum that can be seen with eyes.

It doesn't include infrared or ultraviolet radiation, because those cannot be seen

with eyes. Only the 'visible' wavelengths can.