Answer : 2. "Uterus"
Explanation :

The uterus is an inverted pear-shaped muscular part of the female reproductive system. It is positioned between the bladder and the rectum. Its function is to nourish and encloses a fertilized egg until the offspring, is ready to be delivered. It is within the uterus that the offspring develops during gestation. Once the egg has left the ovary it undergoes fertilization and implants itself in the lining of the uterus. The key function of the uterus is to provide nourishment to the developing fetus prior to birth. Thus, the baby is born as a result of rhythmic contraction of muscles in uterus.