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.

[EX Q]: Which unit is used to express the amount of energy in food?  
 (A) Calorie (B) degree Celsius (C) milliliter (D) gram
[EX A]: A

[EX Q]: What is the name of the product formed from the reaction shown below? 4Fe(III) + 3O_{2} -> 2Fe_{2}O_{3}  
 (A) iron (II) oxide (B) iron (III) oxide (C) oxygen ferrite (D) diferrous trioxide
[EX A]: B

[EX Q]: Which of the following could help to reduce a home heating bill in winter?  
 (A) replacing wood doors with aluminum doors (B) using more insulation in the walls of the home (C) removing thick rugs and heavy curtains in the home (D) painting the roof of the home white to reflect light
[EX A]:
B