You are given a science question (hard-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.

Carolina wrens and painted buntings are two bird species that live in overlapping territories. They have different requirements for food and nesting. Which term best describes the relationship between the two species?  
 (A) parasitism (B) symbiosis (C) coexistence (D) mutualism
C

Sonar equipment sends waves into deep water and measures the  
 (A) time delay of the reflected waves. (B) refraction of the transmitted waves. (C) direction of the transmitted waves. (D) interference of the transmitted and reflected waves.
A

Which of these will form new soil the fastest?  
 (A) A log rotting in a forest. (B) Water running in a stream. (C) A rock sitting in a garden. (D) Waves breaking on a beach.

A

