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.

One hot summer, a grassland experienced a drought. Which most likely happened in the ecosystem during this time?  
 (A) The competition for food among primary consumers increased. (B) Nutrients cycled through the system at a faster rate. (C) Less solar radiation was able to enter the system. (D) Secondary consumers became extinct.
A

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
C

What type of graph would be best for recording plant growth over a one-week period?  
 (A) pie chart (B) line graph (C) scatterplot (D) histogram

B