Basically they ask you which option would be better (0.5 more capacity, 4 more storage, or 500 more hours processing)
To find out which is better you just need to multiply these numbers by their respective shadow price's:
Capacity: 0.5*23,333.33 = 11,666.67
Storage: 4*3833.33 = 15,333.32
Processing: 500*0 = 0
We can see here that the storage option is the better one!
Hope this helped :)