question: mammals:terrestrial animals
choices.label: A B C D
choices.text: spacecraft:vehicle flowering plants:flowerless plants interstellar matter:sirius polar bear:polar penguin
explanation: "mammals" can be "terrestrial animals" and "terrestrial animals" can be "mammals". "spacecrafts" can be "vehicles" and "vehicles" can be "spacecrafts". "flowering plants" and "flowerless plants" are two kinds of plants, which are completely complementary. "interstellar matter" is a general term for the matter and radiation fields that exist between galaxies and stars. "sirius" is a star, and "interstellar matter" and "sirius" have no obvious logical relationship. both "polar bears" and "polar penguins" are animals.
relation: mammals terrestrial animals R2.7
relation: spacecraft vehicle R2.7
relation: flowering plants flowerless plants R2.5
relation: polar bear polar penguin R2.6