The part of the electromagnetic spectrum that has the longest wavelengths is .

RADIO WAVES

Explanation:

As we know that energy of electromagnetic waves and its wavelength is related by the formula

so here as we can see that energy is inversely depends on wavelength so for the longest wavelength the energy is least.

So here we know that least energy electromagnetic waves are Radio waves.

So the longest wavelength must be corresponding to least energy electromagnetic waves

So here correct answer for longest wavelength will be

RADIO WAVES

this is a good question! i'll do some research and come back when i have the answer!

a and c

c is 100% but i am confused in a