Which wave lies adjacent to the low frequency portion of the visible spectrum a. gamma rays
b. infrared
c. x rays
d. ultraviolet rays

b. infrared

Explanation:

The visible light with the smaller frequency is associated with the color red.

While the blue is the one with the larger frequency.

Now, as the name says, infrared waves are the ones with a frequency just below the one of the red visible light.

Where the frequency of the red light is something around (4.3*10^14 Hz)

and the frequency of the infrared waves is in the range between (10^12 Hz and 10^14 Hz)

Then the correct option is b, infrared.