question: root:tree
choices.label: A B C D
choices.text: umbrella; umbrella stand gear; crank wall footing; house bamboo knot; bamboo leaf
explanation: a "root" is a part of a "tree". "umbrella" is not a part of the "umbrella stand". both "gear" and "crank" are mechanical elements, "gear" is not part of "crank". the "wall footing" is part of the "house". both "bamboo knots" and "bamboo leaves" are part of bamboo, and "bamboo knots" are not part of "bamboo leaves".
relation: root tree R2.3