PART A)
As we know that energy of light depends on its wavelength and frequency as following formula
now we know that wavelength of blue light is less than the red light so here energy of blue light will be more
also we know that
so here if wavelength is smaller for blue light so its frequency will be high and the speed of both light will be same in same medium
PART B)
Since we know that frequency of blue light is more than red light as well as wavelength of blue light is less than the wavelength of blue light so here blue light will have more energy
When blue light and red light strike the metal surface then due to more energy of blue light it will release some loosely bonded electrons from metal surface which will contribute in current.
here if we increase the intensity of light then the number of photons that contain the blue light of certain energy will be more and that will contribute more current
So here quantification help as we know that due to quantization only certain frequency or energy will lead to eject electron so all colours will not give this current