All electromagnetic energy (light), including gamma rays through radio waves, has what in common?

A. Speed
B. Wavelength
C. Frequency
D. Energy
E. Amplitude

I think a

2 answers

All waves have same speed in a vacuum of 3E8 m/s.
All have a wavelenth although each is different.
All have a frequency although each is different.
All have energy although each is different.
They all have amplitude that depends upon intensity.
In short all could be true. I think it's a lousy question but I would go with a also.
It was A