Restore is what I think it would be. Either that or it means to change it, make it better.
If the price of Sprite increases, the demand for a substitute good like 7-up will increase too, because people will seek for a substitute product to replace Sprite.
<u>Law of demand</u> explains the higher the price of a good, the less people will demand it (or avoid it), and will seek others to replace it.
I am pretty sure it is d.