Protons and neutrons strongly attract when they
a. are moving fast.
c. are at high energies.
b. are very close together.
d. have opposite charges. protons and neutrons strongly attract when they:
b. are very close together.

I think the correct answer from the choices listed above is option C. Protons and neutrons strongly attract when they are at high energies. Protons and neutrons are held together in a nucleus of an atom by the strong force. Hope this answers the question. Have a nice day.

Initial velocity,  u = 4.9 m/sfinal velocity = v m/sinitial height,  h₁ =  245 m    final height, h₂ = 0a = -9.8  m/s²time taken = t secondss = ut + 0.5at²⇒  (h₂-h₁) = ut + 0.5at²⇒  0-245 = 4.9t + 0.5×(-9.8)×t²⇒ -245 = 4.9t - 4.9t²⇒ 4.9t² -4.9t -245 =0solving it, we get   t = 7.59sv  = u +  at = 4.9 -9.8×7.59 = 4.9 - 74.38 = -69.48 m/svelocity is  69.48 m/s downward