Propulsion efficiency of propeller drive aircraft is

Question

Direction: Each of the next consists of two statements, one labeled as the ‘Assertion (A)’ and the other as carefully and select the answers to these item using the codes given below:

1. Both A and R are individually true and R is the correct explanation of A
2. Bothe 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

 Assertion (A):  Propulsion efficiency of propeller drive aircraft is low at very high speeds.                              

Reasons (R):  At high speeds, shock waves are formed over propeller blades