Answer the following question given this paragraph: 

Water is the only substance on Earth that is present in all three states of matter. This means that water is present as a solid, liquid, and gas. Earth is the only planet where water is present in all three states. All three phases may be present in a single location or in a region. The three phases are solid (ice or snow), liquid (water), and gas ( water vapor ). See ice, water, and clouds pictured below ( Figure below ).


Q: What is the only substance on earth that is present in all three states of matter?


A:
water