Which of the following best describes trends in hominid evolution that took place over millions of years, from early ancestors to modern humans? a) their brain cavity increased in size, their overall body size decreased, and they became less reliant on vision. b) their jaw became more parabolic in shape, their gestation period increased, and they evolved to walk upright. c) their overall body size decreased, their brow became lower, and their average litter size increased d) their tooth size increased, their brain size increased, and their hind limbs became longer.