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.

A girl signals her friend by shining a flashlight on a mirror. Her friend can see the signal because
(A) heat energy can be transferred from one object to another (B) mechanical energy can be transferred from one object to another (C) sound energy can be reflected from one object to another (D) light energy can be reflected from one object to another
D

What has occurred when bubbles form in a liquid that is being heated?
(A) Oxygen is absorbed from the air. (B) Heat is radiating in the liquid. (C) The boiling point has been reached. (D) Molecular stability in the liquid is increasing.
C

Clouds are formed from tiny drops of water that are light enough to float in the air. As these drops bump into each other, they form larger drops. What happens when these drops become too heavy to float in the air?
(A) The drops form fog. (B) The drops evaporate. (C) The drops fall as rain. (D) The drops become air.
C