Julie's Mom Had Her Begin Receiving Vaccinations in Her First

Julie's mom had her begin receiving vaccinations in her first months of life.She did this because she knows

A) Julie's immune system is developing and it will make her less vulnerable to disease.
B) insurance pays to vaccinate babies.
C) the pain response is not fully developed and it will cause less pain now than if she waits until she is older.
D) this action will desensitize her to needles so she won't have a phobia about them.