The correct answer is C) rapid expansion as water absorbs heat and changes to steam. When water is used as a fire extinguishing agent, the rapid expansion that occurs as water is converted from a liquid to a vapor state is a definite advantage. As water absorbs heat from the fire, it undergoes a phase change and quickly expands into steam, which helps to smother the fire by displacing oxygen and cooling the surrounding area. This rapid expansion of water into steam is an effective way to extinguish fires, making it a valuable characteristic of water as a fire extinguishing agent. The other answer choices do not accurately describe the advantageous property of water in fire extinguishing. Option A describes the alternating expansion and contraction of water, which is not the primary advantage. Option B describes rapid contraction, which is the opposite of what actually occurs. Option D mentions absorption of smoke and gases, which is not the main advantage of water's phase change.