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.

[EX Q]: Some events on Earth happen instantly while others take thousands of years to occur. Which process takes the longest time to complete?  
 (A) rivers rising due to storms and floods (B) evaporation of water from the leaves of a plant (C) weathering of a rock to form small rocks and sand (D) movement of small pieces of rock by flowing water
[EX A]: C

[EX Q]: One substance found on Earth is more stable as an elemental gas than as part of a solid compound. As a result, this substance is very abundant in the atmosphere. Which substance exhibits these traits?  
 (A) argon (B) chlorine (C) nitrogen (D) oxygen
[EX A]: C

[EX Q]: All natural resources on Earth are either renewable or nonrenewable. Whether a resource is renewable or nonrenewable depends on how fast or slow the resource is replaced. If the resource is used faster than it is replaced, then the resource will, in time, disappear. Which statement describes the use of a renewable natural resource?  
 (A) A home burns natural gas for heat. (B) A city burns coal to generate electricity. (C) A farmer plants different types of crops to protect the soil. (D) A construction crew builds a road from rock, sand, and gravel.
[EX A]:
C