A. constant angle of attack and variable mach number
B. constant angle of attack and constant mach number
C. constant angle of attack and constant altitude number
D. constant mach number and constant altitude number
This question was posed to me during an interview.
Question is from Cruise Method 3 in portion Cruising Performance of Aircraft Performance
Easiest explanation: Cruise method 3 also known as constant altitude and constant mach number method. In cruise method 3 altitude, mach number and relative airspeed are kept constant i.e. M, u and h are constant throughout the method.