Naturalist: There have been recent claims that the Tasmanian tiger is not extinct. However this is not true. The habitat of these tigers was taken over for sheep farming and grazing decades ago. This resulted in the systematic extinction of the tiger from its habitat. Moreover, no hard proofs of its survival such as carcasses or tracks are found by the naturalists. Though sometimes, somewhere the animal is sighted, the Tasmanian tiger no longer exists.
Which one of the following is an assumption on which the naturalist's argument depends?
A. Sheep farming drove the last Tasmanian tigers to starvation by chasing them from their natural habitat.
B. Some scavengers in Tasmania are capable of destroying tiger carcasses without a trace.
C. Every naturalist working in the Tasmanian tiger's natural habitat has looked systematically for hard core evidence of the tiger's survival.
D. The Tasmanian tiger did not make a major move and adapt a different habitat when his habitat was taken over by sheep.
E. Those who have reported sightings of the Tasmanian tiger are not experienced naturalists.