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.

Example Input: A hardware designer finds that the wiring in a circuit is releasing enough heat to make the circuit dangerously hot. Which change would best solve this problem?  
 (A) increasing the current in the circuit (B) placing rubber insulation on wires in the circuit (C) reversing the direction of current flow in the circuit (D) using circuit wires with a lower resistance
Example Output: D

Example Input: What is an environmental threat posed by oil and gas acquisition and transport that is not posed by the acquisition and transport of the energy resources uranium, and wood?  
 (A) habitat change (B) vehicle pollution (C) pipeline leaks (D) soil compaction and loss
Example Output: C

Example Input: A student is investigating the effect of different nutrients on the growth of seedling plants. Which of these would be an independent (manipulated) variable in the investigation?  
 (A) water (B) sunlight (C) soil nutrients (D) seedling plants
Example Output:
C