electromagnetic radiations are of various energy range
this energy of electromagnetic waves will depend upon its frequency as well as wavelength
so we will have
[tex]E = \frac{hc}{\lambda}[/tex]
or we can say
[tex]E = h\nu[/tex]
so here we can say that all electromagnetic waves must have different energy due to which wavelength and frequency must be different
now we also know that intensity depends on energy and it directly proportional to amplitude of wave
so for different electromagnetic radiation we will have different amplitudes
but we also know that speed of electromagnetic waves will change on changing the medium of wave
so here velocity of wave will remain same for all range in vacuum
so correct answer will be
E. velocity