Answer:
C. Placental mammals
Step-by-step explanation:
The placentals are the largest group of mammals, totally dominating the class and terrestrial habitats.
Amnium, the fluid that protects the embryo from adhesions and shocks, is installed in the female's uterus for development with the help of a placenta that provides fixation and nutrients.
This breeding method, although producing a smaller number of offspring per pregnancy, has a high success rate, allowing greater chances of survival to offspring.