TASK DEFINITION: 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.
PROBLEM: Lichens are symbiotic organisms made of green algae and fungi. What do the green algae supply to the fungi in this symbiotic relationship?  
 (A) carbon dioxide (B) food (C) protection (D) water

SOLUTION: B

PROBLEM: The shape of a riverbed changes over time as a result of which gradual process?  
 (A) erosion (B) dissolving (C) plate shifting (D) compaction

SOLUTION: A

PROBLEM: Which of the following is performed by the quality control division of a company that is manufacturing a chair?  
 (A) applying the varnish (B) assembling the parts (C) cutting the material (D) inspecting the finish

SOLUTION:
D