A vector `barP` is along positive x axis, if `barQ` is another vector such that `(barP * barQ)` is zero, then Q should be

Options

A. In an elastic collision, the final kinetic energy is equal to initial kinetic energy of the system
B. In an elastic collision, the final linear momentum is equal to initial linear momentum of the system
C. In an elastic collision, the linear momentum of system remains constant
D. In an elastic collision, the kinetic energy of system remains constant