Two putty balls of equal mass moving with equal velocity in mutually perpendicular direction, stick together after collision. If the balls were initially moving with a velocity of `45sqrt(2)jms^(-1)` each, the velocity of their combined mass after collision is
A. `45sqrt(2)ms^(-1)`
B. `45ms^(-1)`
C. `90ms^(-1)`
D. `22.5sqrt(2)ms^(-1)`
