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: Which illness is always caused by an infection?  
 (A) a heart attack (B) a broken bone (C) influenza (D) cancer

SOLUTION: C

PROBLEM: When air rises over the open ocean, a low pressure system is formed. Which factor increases the potential of a low pressure system developing into a hurricane in the Northern Hemisphere?  
 (A) cool ocean currents circulating towards the equator (B) increased volcanic activity in the upper latitudes (C) cold air moving south from the North Pole (D) warm water temperatures in the tropics

SOLUTION: D

PROBLEM: Which best describes the characteristics of a river basin?  
 (A) the land drained by a river and its tributaries (B) the land formed when rivers create estuaries and marshes (C) the land at the mouth of a river where water flows into the ocean (D) the land formed as a result of a river flooding

SOLUTION:
A