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.

Some scientists believe that the mass extinction of dinosaurs was caused by the impact of a large meteorite on Earth. This impact would have caused a darkening of the sky due to dust blown into the upper atmosphere. This darkening would have reduced the sizes of some ecosystems because of
(A) longer seasons. (B) accelerated erosion. (C) reduced photosynthesis. (D) increased number of hurricanes.
C

Which step will most likely ensure that the results of an investigation are valid?
(A) using a computer to graph results (B) verifying that results match the original hypothesis (C) comparing the results with those of other scientists (D) eliminating any results that appear to be abnormal
C

A student is dropping objects of various sizes and shapes and recording the time it takes for each object to hit the ground. Which question is the student most likely trying to answer?
(A) What force slows some objects down? (B) What force pulls objects to the ground? (C) Do some objects fall more quickly than others? (D) Do objects break or bounce when hitting the ground?
C