Final answer:
Understanding Della and Jim's relationship underscores the central idea of sacrifice and love in 'The Gift of the Magi.'
Step-by-step explanation:
The understanding of Della and Jim's relationship underscores the central idea of sacrifice and love. In the story, 'The Gift of the Magi,' Della and Jim both make sacrifices to buy meaningful gifts for each other, which highlights their deep love and affection. Their selflessness and willingness to give up their most treasured possessions for the happiness of their partner illustrate the theme of love and sacrifice.