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.
--------
Question: Water at 20°C in an uncovered pan is evaporating very slowly. What could be done to the water to make it evaporate more quickly?  
 (A) Cover it. (B) Heat it. (C) Place it in the dark. (D) Put salt in it.

Answer: B


Question: When iron combines with oxygen in a moist environment, rust forms because of a  
 (A) chemical reaction. (B) physical reaction. (C) change in density. (D) change in temperature.

Answer: A


Question: On which date does North America usually experience the longest period of daylight?  
 (A) March 21 (B) June 21 (C) September 21 (D) December 21

Answer:
B