Why do placental mammals have a reproductive survival advantage over reptiles?
(A) A placenta allows the birth of developed young instead of laying eggs.
(B) A placenta nourishes new mammal young, while reptile young must find food.
(C) Placental mammal eggs resist cracking better than reptile eggs.
(D) Placental mammal can have a greater number of young than reptiles.
I already know D isn’t the answer! I’m thinking it’s either A or B.
