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.

The teacher heats a pot of water. Once the water reaches 100°C, which point has the water reached?  
 (A) boiling (B) melting (C) freezing (D) evaporating
A

Plants growing in a pond release a gas that fish need to survive. Which gas do the plants release that fish use?  
 (A) helium (B) hydrogen (C) nitrogen (D) oxygen
D

In a northern state, a room used for growing plants is not allowing enough light to enter for healthy plant growth. Adding windows in walls facing which direction would best solve this problem?  
 (A) north (B) south (C) east (D) west

B