ANS:C - both (a) and (b)

Ethanol is produced by continuous fermentation. In Brazil, which was the largest exporter of ethanol, they use sugarcane, however in countries like the USA they use corn. Corn is far cheaper to grow than sugarcane, however Brazilian farmers say that they get more than twice as much ethanol per hector to what cornn can. America but a tarrif on american sourced sugarcane based ethanol because of the domestic modity prices. This is double the price of corn based ethanol.