4 Peanut butter has an upward-sloping supply curve and a downward-sloping demand curve.

If a 10 cent per kilo tax is increased to 15 cents, the government's tax revenue a increases by less than 50 per cent and may even decline.

b increases by exactly 50 per cent.

c increases by more than 50 per cent.

d depends on whether supply or demand is more elastic.