Using the symbols provided in the palette below, the expression for the total momentum of the system in cartesian unit-vector notation is:
a) p = Σ(mv)
b) p = Σ(p_i)
c) p = Σ(p_1) + Σ(p_2) + Σ(p_3)
d) p = Σ(p_x) + Σ(p_y) + Σ(p_z)