A 42-Kg Object,initially at Rest,"explodes" into Three Objects of Equal Mass

Multiple Choice

A 4.2-kg object,initially at rest,"explodes" into three objects of equal mass.Two of these are determined to have velocities of equal magnitudes (5.0 m/s) with directions that differ by 90 $\degree$ .How much kinetic energy was released in the explosion?

A) 70 J
B) 53 J
C) 60 J
D) 64 J
E) 35 J