Answer
(b) Linear momentum has units of $\mathrm{kg.m/s}$.
Work Step by Step
Momentum is a product of mass and velocity which gives it a unit of $\mathrm{kg.m/s}$.
In terms of $\mathrm{N}$ which effectively is $\mathrm{kg.m/s^2}$, momentum is $\mathrm{N.s}$.