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: Scientists found fish fossils in the desert. What do the fossils tell about this environment when the fish were alive?
(A) There was a forest with large trees. (B) There were lakes with water plants. (C) There were mountains with glaciers. (D) There was a desert with large rocks.

SOLUTION: B

PROBLEM: Why are some rocks smoother and rounder than others?
(A) They have the shapes of the minerals from which they are made. (B) They were smoothed by the action of wind and water. (C) They were squeezed up through the soil. (D) They hardened in rounded pockets of soil.

SOLUTION: B

PROBLEM: Which best describes the role of the esophagus in digestion?
(A) It releases acid and mixes food. (B) It aids in absorption of nutrients from food. (C) It carries food from the mouth to the stomach. (D) It carries food from the stomach to the intestines.

SOLUTION:
C