Two objects of masses `m` and `4m` are at rest at an infinite separation. They move towards each other under mutual gravitational attraction. If `G` is the universal gravitaitonal constant, then at separation `r`
A. The tatal energy of the two object is zero
B. Their relative velocity of approach is `((10Gm)/(r))^(1//2)` amplitude
C. The total kinetic energy of the object is `(4Gm^(2))/(r)`
D. Net angular momentum of both the particles is zero about any point