About two million years ago, lava dammed up a river in western Asia and caused a small lake to form. The lake existed for about half a million years. Bones of an early human ancestor were recently found in the ancient lake-bottom sediments on top of the layer of lava. Therefore, ancestors of modern humans lived in Western Asia between 2 million and 1.5 million years ago.

Which one of the following is an assumption required by the argument?

(A) There were not other lakes in the immediate area before the lava dammed up the river.

(B) The lake contained fish that the human ancestors could have used for food.

(C) The lava under the lake-bottom sediments did not contain any human fossil remains.

(D) The lake was deep enough that a person could drown in it.

(E) The bones were already in the sediments by the time the lake disappeared.

The sediments could have had the required number and quality of human bones in it which would make it even more easier to understand that human ancestor could have lived there for a much longer time, and along with that the lava could have been there after the sediments contained any of the fossils in the area.

Parrain Parrain · Answer 2 · 2021-12-31T13:58:36+01:00

In order to make the assumption described, (E) The bones were already in the sediments by the time the lake disappeared.

The assumption is that modern humans lived between 2 million and 1.5 million year ago and the lake was formed two million years ago and lasted for half a million years till 1.5 million years ago.

This assumption is true because the fossil was found at the bottom of the lake which means that humans must have been in the area before the lake disappeared 1.5 million years ago for the fossil to have sank to the bottom of the lake.

In conclusion, option E is correct.

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