question: oxygen:breathe
choices.label: A B C D
choices.text: watch:time brain:think sun:light weapon:war
explanation: to "breathe", there must be oxygen. "watch" can "time". without a "watch", one can also "time". to "think", there must be a brain. "sun" can "light". without the "sun", one can also "light" with other objects. "weapons" can be used for "wars", and "wars" can happen without "weapons", such as trade "wars".
relation: oxygen breathe R5.4
relation: brain think R5.4