Between 6 and 7 million years ago, the lineage that led to hominins split from the lineage that led to chimpanzees. Which of the following best describes one of the ways that hominins evolved? A. Hominins evolved a smaller skull and smaller brain capable of designing tools. B. Hominins evolved an opposable thumb that enabled hands to grasp objects. C. Hominins evolved shoulder bones that enabled them to walk faster on all four limbs. D. Hominins evolved more chromosomes that enabled them to reason and solve problems.