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: When a hammer strikes a nail, the nail  
 (A) exerts balanced forces that helps it from moving. (B) exerts a force equal to the weight of the hammer. (C) exerts an unbalanced force that changes its velocity. (D) exerts an equal and opposite force back on the hammer.

SOLUTION: D

PROBLEM: How is xylem similar to phloem in a plant?  
 (A) They both take in water from the soil. (B) They both transport materials through the plant. (C) They both make sugar in the leaves. (D) They both store waste products in the plant cells.

SOLUTION: B

PROBLEM: Large populations of tortoises inhabited the Galapagos Islands before humans. When humans settled on the islands and introduced goats, the number of tortoise declined. What is most likely the explanation for the decrease in the tortoise population?  
 (A) Goats consume tortoise hatchlings. (B) Goats pollute water sources. (C) Goats compete with tortoises for vegetation. (D) Goats contribute to soil erosion.

SOLUTION:
C