Until the arrival of European settlers some 200 years ago, Australia lagged behind New Guinea in the development of human societies. Why, according to Guns, Germs, and Steel, was animal husbandry and agriculture slower to develop among the native Australians?
a. The aboriginal hunter-gatherer populations had little resistance to European germs and thus were drastically reduced in numbers by diseases after the initial outside contact.
b. Among all the earth's continents, Australia was the driest and had the least fertile soils. There were few domesticable plants and no native domesticable animals.
c. The continent was too isolated by water that was only crossed by boats at a later stage of development than New Guinea.
d. The aboriginal hunter-gatherer groups were too strong as competitors to farming groups, who thus made very slow progress.
The answer to this can be found in Chapter 15 of Guns, Germs, and Steel. Specifically, it can be found beginning on p. 308 of the paperback edition of the book. When thinking about the answer to this question, we should remember the basic thesis that Diamond is putting forward in this book. His basic argument is that geography is the determining factor for which areas get agriculture and which do not. Because of this, Option B is the correct answer. In fact, the wording of Option B is almost exactly the same as the wording on p. 308.
According to Diamond, animal husbandry was not going to work in Australia. The problem is that Australia essentially had no animals to domesticate. Diamond says that all of the
…candidates for animal husbandry disappeared in the wave of extinctions (or exterminations) that accompanied human colonization of Australia.
No domesticable animals means no animal husbandry.
Diamond also tells us that Australia was not very good for agriculture. One problem is that Australia is
…not only the driest continent but also the one with the most infertile soils.
He later goes on to tell us that Australia had very few plants that were good for domestication. In these ways, we can see that Diamond would say that Option B is the correct answer.