Bovine remains found in a certain region of Africa date back to a time when the climate was arid. While there were people in the region at this time, there were no other large mammals there. Any natural sources of water available to these bovines would have brought other large mammals to the area. Thus, these bovines had been domesticated and the people living in the region were no longer exclusively hunter-gatherers.
Which one of the following is an assumption on which the argument depends?The argument says there were bovines in an arid region, but no other large mammals. Since natural water sources would have attracted other large mammals too, the argument suggests that the bovines were not surviving there through natural water sources.
The key missing link is that wild bovines would probably not be there without natural water, so their presence is best explained by human care or
domestication.
(A) Unless they are domesticated, bovines are unlikely to exist in a region where there are no natural sources of water available to them.
This is correct. If wild, undomesticated bovines could easily live in a region with no natural water sources, then the argument would lose its reason for concluding that these bovines were domesticated.
(B) Domesticating animals is one of the first practices that a society must adopt in order to change from hunting and gathering to agriculture.
This is not required. The argument does not need to show the full transition to agriculture; it only concludes that the people were not exclusively hunter-gatherers.
(C) With the help of humans, other large mammals would have been able to inhabit this arid region.
This is irrelevant. The argument is about why bovines were present despite the absence of other large mammals.
(D) No human culture obtains food both through agriculture and through hunting and gathering.
This is far too strong. The argument only says these people were not exclusively hunter-gatherers; it does not need to deny that mixed food systems exist.
(E) Domesticated animals of a given size do not need as much water as do wild animals of comparable size.
This is not required. The issue is not whether domesticated bovines need less water, but whether humans could have helped them survive where natural water sources were lacking.
Answer: (A)