[" r particles,each of mass "M" and equidistant from each other,move along a circle of radius "],[" ader the action,of their mutual gravitational attraction.The speed of each particle is "],[[(GM)/(R)," (B) "sqrt(2sqrt(2)(GM)/(R))," (C) "sqrt((GM)/(R)(1+2sqrt(2)))," (D) "(1)/(2)sqrt((GM)/(R)(1+2sqrt(2)))]]