question: river:water
choices.label: A B C D
choices.text: desert:mud forest:trees grassland:animals mountains:snow and ice
explanation: "water" is an inevitable part of "river", and "water" is part of "river" an inevitable part of "desert" is not "mud", and "mud" is not part of "desert" "trees" are an inevitable part of "forest" and "trees" is a part of "forest" where "animals" live may be "grassland", "animal" is not part of "grassland" "mountains" may be covered with "snow and ice" and "snow and ice" is not part of "mountains"