A stationary partical explodes into two partical of a masses `m_(1) and m_(2)` which move in opposite direction with velocities `v_(1) and v_(2)`. The ratio of their kinetic energies `E_(1)//E_(2)` is
A. `m_2//m_1`
B. `m_1//m_2`
C. 1
D. `m_1v_2//m_2v_1`