Cooling the car

This task is about deciding which car is the coolest and why.
These cars were parked in a sunny supermarket car park for the same length of time.
The driver's car windows had been left open at different heights.
 
cooling-car-A.png
Cooling-car-B.png
cooling-car-C.png
cooling-car-D.png
 

Question

a)  Which car will be the coolest inside after one hour? 
    • cooling-car-A.png

    • Cooling-car-B.png

    • cooling-car-C.png

    • cooling-car-D.png

b) Explain fully what happens to cool this car