Consider the following statements pertaining to a convergent-divergent nozzle flow with Mach number 0.9 at the throat:
1. The flow is subsonic in both the converging and diverging sections
2. The Mach number at the exit is less than one
3. In the diverging section, the flow is supersonic
4. There is a shock in the diverging section
Which of the above statements are correct?
a) 1 and 4 (b) 1 and 2
(c) 3 only (d) 3 and 4