Final answer:
The doctrine described in scripture that addresses humanity's separation from God and provides a solution is reconciliation, representing the mending of the relationship between God and humans through Jesus Christ's sacrifice.
Step-by-step explanation:
The doctrine described in scripture that provides a solution to humanity's separation from God due to the Fall is d) Reconciliation. In Christian theology, reconciliation refers to the restoration of a relationship between God and humanity that was broken due to sin. This concept is deeply rooted in the New Testament, where the atonement brought forth by Jesus Christ's sacrifice is seen as a bridge to reconcile humans with God, overcoming the separation caused by original sin. The other options, such as regeneration, adoption, and justification, discuss other aspects of salvation but do not directly refer to the mending of the relationship between God and man.