C.an equal and opposite reaction
The change in gravitational potential energy due to change in position must be the change in it's kinetic energy as the system is isolated! so find out the potential energies of the two different points!
<span>PE=−[G<span>M1</span><span>M2</span>]÷R
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Potential energy of a particle due to mass A is not affected by presence of any other mass B !</span>
