instruction:
You are given a science question (easy-level) and four answer options (associated with "A", "B", "C", "D"). Your task is to find the correct answer based on scientific facts, knowledge, and reasoning. Do not generate anything else apart from one of the following characters: 'A', 'B, 'C', 'D'. There is only one correct answer for each question.
question:
A large number of species on Earth became extinct during a short time period about 65 million years ago. Based on this pattern of extinction, which is the most likely cause?  
 (A) gradual climate change (B) continued climate stability (C) sudden global climate change (D) gradual ecosystem succession
answer:
C


question:
Which of these will most likely result from small meteoroids entering the atmosphere of Earth?  
 (A) a decrease in air temperature (B) the appearance of shooting stars (C) an decrease in atmospheric ozone (D) the appearance of the Northern Lights
answer:
B


question:
Above a continent, a warm air mass slowly passes over a cold air mass. As the warm air begins to cool, clouds form. What will most likely happen next?  
 (A) Rain will fall. (B) Hurricanes will form. (C) Lightning will strike. (D) Hail will form.
answer:

A