Between 2006 and 2007, the price of skimmed milk powder on the world market rose from $\$ 1000$ per tonne to $\$ 2400$ per tonne.
Assuming that the market is a free market, what will result from the price change?
1 )
Consumers will buy more complements to skimmed milk powder.
Farmers will increase the size of their dairy herds to supply more milk.
3 )
Firms processing milk into skimmed milk will switch to producing substitutes.
4 )
Governments will introduce a system of rationing.
