Answer:
So Bob provide maximum impulse to the car
Step-by-step explanation:
As we know that impulse is defined as change in momentum
so here we have


so here we can say that 

1), Arnold exerts a force of 300 N for three seconds, 
So impulse due to force of Arnold


2). Bob exerts a force of 500 N for two seconds, 
So impulse due to force of Bob


3). Cecil exerts a force of 200 N for four seconds.
So impulse due to force of Cecil

