Among the various pre-Australopithecine species of early hominins that existed between 4 and 7 million years ago, which of the following statements is correct?
A. They displayed advanced tool-making capabilities.
B. Bipedalism was not a characteristic feature during this period.
C. Increased brain size was a defining trait of these hominins.
D. The emergence of Homo habilis marks the beginning of this timeframe.