9708/11 Economics Oct Nov 2012 Online Test | Cambridge AS and A Level MCQ

In the diagram, the supply curve shows the number of spaces in a car park and the demand curves show the demand for spaces on four different days, $D_1$, $D_2$, $D_3$ and $D_4$.
The owner wishes to charge a parking fee on each of these days to allocate the spaces according to the market mechanism.
Which pricing policy should the owner use?