In this task, you are given a multiple-choice question and you have to pick the correct option. Answer with option indexes (i.e., "A", "B", "C", and "D").

[EX Q]: What is a source of oxygen through photosynthesis? (A) lakes (B) car engines (C) sunflowers (D) people
[EX A]: C

[EX Q]: A storm ravages a town for a week straight, complete with deluges of rain. If someone in that town needs a source of water, it is (A) everywhere (B) missing (C) in short supply (D) rare
[EX A]: A

[EX Q]: An example of a change in the Earth is when a volcano, resembling a tall mountain, violently explodes and (A) turns a deep crater into igneous rock and ice (B) gushes upward, revealing mounds of snow (C) drops downward, becoming a huge lake of lava (D) fills a deep crater with very hot water
[EX A]:
C