The fact about Poe's background that contributes most to an understanding of "To One in Paradise" is:
C) Poe's wife, Virginia, died at the young age of 24 after she contracted tuberculosis five years before.
This option is significant because "To One in Paradise" expresses themes of loss and longing, which are deeply tied to Poe's personal experiences with the death of loved ones. Virginia's death had a profound impact on Poe's work and his exploration of grief and sorrow.