Who is the Immaculate Conception and why?

Mary, the Mother of God, is the Immaculate Conception. This is because she was chosen by God and given the grace of being preserved from original sin.

Pope St. John Paul II said,

Man looks on the outward appearance, but the Lord looks on the heart” (1 Sm 16:7). And Mary’s heart was fully disposed to the fulfilment of the divine will. This is why the Blessed Virgin is the model of Christian expectation and hope... In her heart there is no shade of selfishness: she desires nothing for herself except God’s glory and human salvation. For her, the very privilege of being preserved from original sin is not a reason to boast, but one for total service to her Son’s redemptive mission.