A bypass jet engine gives a better propulsive efficiency and better fuel economy

Question

Assertion (A): A bypass jet engine gives a better propulsive efficiency and better fuel economy than a straight jet engine.            

Reason (R): A bypass jet engine given lower velocity of jet efflux than a straight jet engine.

1. Both A and R are indidually true and R is the correct explanation of A
2. Both A and R are individually true but R is not the correct explanation of A
3. A is true but R is false
4. A is false but R is true