The most apparent change during the evolutionary history of Homo sapiens is traced by
A. Remarkable increase in the brain size
B. Loss of body hair
C. Walking upright
D. Shortening of the jaws

Hint: Homo sapiens is the most evolved species in humans and as we compare ourselves with the earlier species of human, we can clearly identify the differences during evolution. Also, the humans have evolved from the common species of the apes and during evolution now they differ.

Complete answer:
This is a well known fact that the apes and homo sapiens or current human shared the same ancestry but during the course of evolution both the organisms went on to develop and adapt themselves according to the situations and the conditions. For humans to be different from the apes, the changes should also be different from each other.
Now we look at the changes mentioned and compare them with the apes and humans we will surely get our answer as the apes are not as well developed as the humans. The first change mentioned is the increase in brain size, the size of the brains of humans have increased as compared to that of the Apes. With the increase in the size of the brain the intelligence of the humans has also increased. By the time and different stages of evolution apart from the apes the human brain has evolved significantly.
The second change mentioned is the loss of body hair, the stages of earlier apes and humans were already differentiable with the appearance of lesser body hair and this not an apparent change as the growth of hairs is genetically dependent. The walking pattern of the earlier humans were upright only but during the time this character grew slowly due to the need to run behind the prey for food requirement with the upright body.
The jaws of earlier humans and the apes were small only because there was not a greater difference in the skull size of the organisms.

Therefore, the correct option is Option A.

Note:
Due to the increase in the brain size and the capacity of the brain the humans were able to develop. Thus, evolved themselves in a much better way than the apes have been able to develop and evolve themselves.