In an inelastic collision involving an isolated system, the final total momentum is

a) more than the initial momentum.
b) exactly the same as the initial momentum.
c) less than the initial momentum.

B) exactly the same as the initial momentum.

Explanation:

An inelastic collision occurs when the elements that collide remain together after the collision, and althogh the kinetic energy is not conserved because is transformed into other kinds of energy (thermal energy, for example), the linear momentum does.  

This means the initial momentum before the collision will be equal to the final momentum after the collision:

exactly the same as the initial momentum.

Explanation:

There are two types of collisions :

1. Elastic collision

2. Inelastic collision

In an inelastic collision, the linear momentum before and after the collision remains conserved while the kinetic energy is not conserved. Some of the energy gets lost in the form of heat, light, sound etc.

So, In an inelastic collision involving an isolated system, the final total momentum is exactly the same as the initial momentum.