Bipedalism, Considered a Key Defining Characteristic That Differentiated Early Hominins

Bipedalism, considered a key defining characteristic that differentiated early hominins from other apes,

A) evolved as a result of anatomical changes caused by an increase in brain size.
B) may have evolved as a result of anatomical changes caused by stone tool manufacturing.
C) was accompanied by a sharp increase in hominins' climbing abilities.
D) resulted in greater exposure to heat stress because on two feet, hominins spent increasingly more time in the open grasslands.
E) perhaps developed in the woodlands but became even more adaptive in a savanna habitat.