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]: if a chemical reaction occurs, it might have been triggered by which of these? (A) a person yelling at it (B) a person walking by it (C) a person looking at it intently (D) a person cranking up the room heater
[EX A]: D

[EX Q]: The cell of a plant when photosynthesizing may most require (A) access to roofless space (B) a complete vacuum in space (C) a room with blackened windows (D) dark basement living quarters
[EX A]: A

[EX Q]: As the population of zebra decreases (A) competition among African wild dogs increases (B) predators learn to swim (C) prey communities get larger (D) prey will be more visible
[EX A]:
A