To solve the problem, it is necessary to apply the concepts related to the change of mass flow for both entry and exit.
The general formula is defined by

Where,
mass flow rate
Density
V = Velocity
Our values are divided by inlet(1) and outlet(2) by





PART A) Applying the flow equation we have to



PART B) For the exit area we need to arrange the equation in function of Area, that is



Therefore the Area at the end is 
Difference exists mainly in the label for x axis.
Explanation:
- Shapes of waveform and vibration graphs are same.
- Vibration graphs shows the particle at a single location in the path of the wave when time passes.
- Waveform graphs shows the particle at multiple locations at a single moment of time.
I believe there are two correct answers, and those answers are A and D