Four particles, each of mass M and equidistant from each other, move along a circle of radius R under the action of their mutual gravitational attraction. The speed of each particle is

Question

$\begin{array}{1 1}(A)\;\sqrt{\frac{GM}{R} (1+2 \sqrt 2)} \\ (B)\;\frac{1}{2} \sqrt{\frac{GM}{R} (1+2 \sqrt 2)} \\(C)\;\sqrt{\frac{GM}{R} } \\(D)\;\sqrt{2 \sqrt 2 \frac{GM}{R} }\end{array} $