When the frequency of an electromagnetic wave increases, its energy a. increases. b. decreases. c. stays the same. d. it depends on the exact type of electromagnetic wave.

When the frequency of an electromagnetic wave increases, its energy also must increase. As this occurs, its speed, wavelength, and amplitude all decreases. So, the correct choice would be A. Increases. 

I hope I was able to satisfyingly answer your question. :)