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:
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.
answer:
C

question:
The ocean minimum zone, or OMZ, is an area from 200 to 600 meters below the ocean's surface. The OMZ is dark and cold, with oxygen concentrations less than 10% of concentrations in surface water. Oxygen concentrations are so low because of bacterial activity that breaks down organic material falling from surface waters. Given the conditions in the OMZ, which of these dissolved gases would you expect to find in large concentrations in this zone?
(A) argon (B) nitrogen (C) carbon dioxide (D) carbon monoxide
answer:
C

question:
Oxygen reacts with iron to produce rust and with hydrogen to produce water. Which statement describes both reactions?
(A) A different mixture is formed in each case. (B) A different solution is formed in each case. (C) Both a change of state and of elements is involved. (D) New molecules are formed but the same elements exist.
answer:
D