The correct answer is - C. Brazil.
Brazil has a large and ever-growing economy. This means that it needs more and more resources in order for the economy to go forward and develop. As a country that has the biggest amount of available biomass in the world, Brazil has been trying to fix this problem with the production of bio-fuels, and in fact, it is the second biggest producer in the world of bio-fuels. But only that it a big producer, Brazil is actually using this bio-fuel, and it is a trend that is becoming bigger and bigger. So Brazil is using its own bio-fuel, but also imports a lot of it, thus being the largest consumer/user of bio-fuel in the world.