question: melody:lyrics
choices.label: A B C D
choices.text: shape:color food:life obligation:responsibility purpose:motivation
explanation: the main components of a song include "melody" and "lyrics". the main components of a painting include "shape" and "color". the necessary condition to sustain "life" is "food". "obligation" and "responsibility" have similar meanings. "purpose" is the result that people want to achieve through activities, and "motivation" is the internal reason that drives people to act.
relation: melody lyrics R2.4
relation: shape color R2.4
relation: obligation responsibility R1.1
relation: purpose motivation R3.10