The correct response for calculating momentum is:
initial and final velocity
Momentum is calculated using the formula:
\[ p = m \times v \]
where \( p \) is momentum, \( m \) is mass, and \( v \) is velocity. In this case, both initial and final velocities can be relevant when considering changes in momentum (such as for impulse scenarios), but the fundamental calculation of momentum itself depends on mass and velocity at a given point in time.