question: cleaning:tidy
choices.label: A B C D
choices.text: review:exam price reduction:benefits greening:environmental protection practice:truth
explanation: the purpose of "cleaning" is to get "tidy". the purpose of "review" is to achieve good results in "exams". the purpose of "price reduction" is to increase sales. "price reduction" can allow consumers to obtain "benefits". "environmental protection" refers to the general term for various actions taken by human beings to solve actual or potential environmental problems. "greening" belongs to "environmental protection". the purpose of "practice" is to test the "truth".
relation: cleaning tidy R5.1
relation: price reduction benefits R3.10
relation: environmental protection greening R2.2
relation: practice truth R5.1