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: Similar types of cells form tissues. What is the next level of complexity formed from the grouping of tissues?  
 (A) organs (B) organelles (C) organisms (D) organ systems

SOLUTION: A

PROBLEM: Which occurs as a result of Earth's tilt on its rotating axis?  
 (A) movement of the tides (B) prevalent or trade winds (C) seasonal changes in the climate (D) light and dark changes of day and night

SOLUTION: C

PROBLEM: As a corn plant ages, its leaves grow. Which process is directly responsible for the growth of these leaves?   
 (A) the division of cells in the plant (B) the release of oxygen from the plant (C) the absorption of carbon dioxide in the stem (D) the transportation of nutrients from the roots

SOLUTION:
A