The centre of the Earth is separated from the centre of the Moon by a distance D. Point P lies on a line joining the centre of the Earth and the centre of the Moon, a distance X from the centre of the Earth. The gravitational field strength at P is zero.

What is the ratio $\frac{{{\text{mass of the Moon}}}}{{{\text{mass of the Earth}}}}$?

A.  $\frac{{{{\left( {D - X} \right)}^2}}}{{{X^2}}}$

B.  $\frac{{\left( {D - X} \right)}}{X}$

C.  $\frac{{{X^2}}}{{{{\left( {D - X} \right)}^2}}}$

D.  $\frac{X}{{D - X}}$

A