The correct answer is - Maternal care for offspring would increase due to a greater investment to protect.
During the hominid evolution, the litter sizes decreased and the gestation period increased, and that has resulted into a slower reproductive cycle. The smaller number of the litter means that the newborns are much more precious in the sense of the survival of the species, as any loss can have a very big negative effect on the future generations.
Because of that, the maternal protection, but also the protection of the father and everyone in the tribe is very big, and the young ones are well taken care of for much longer periods of time than before. That has made the hominid youngsters very dependent on the elderly for over a decade for their survival, thus prolonging their independence and ability to survive on their own.