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.

Alex looked at an electric toothbrush that had a plug with three metal prongs. Why are these prongs made out of metal?  
 (A) Metal doesn't get hot and melt when you plug it into the outlet. (B) Metal is strong and is less likely to break when you plug it into the outlet. (C) Metal is an insulator and prevents shocks when you plug it into the outlet. (D) Metal is a conductor and completes a circuit when you plug it into the outlet.
D

A dish of sugar water was left on a window sill. One week later, there were only sugar crystals left in the dish. The water was gone. The best explanation for the appearance of sugar crystals is  
 (A) some of the water was absorbed by the dish. (B) the air condensed. (C) the light shining on the window sill produced more sugar. (D) the water evaporated.
D

The nose, mouth, and diaphragm are parts of which body system?  
 (A) digestive (B) muscular (C) circulatory (D) respiratory

D