Answer:
Option D
Explanation:
Net force acting on anyone particle M,

=GM2(2R)2+GM2(R√2)2cos450+GM2(R√2)2cos450
=GM2R2(14+1√2)
this force will equal to centripetal force.
So, MV2R=GM2R2(14+1√2)
v=√GM4R(1+2√2)
=12√GMR(2√2+1)
Hence, speed of each particle in a circular motion is
12√GMR(2√2+1)