C. The area of the US doubled
Answer:
It can appear in solids, liquids, gases and plasma.
Explanation:
Water is odourless, tasteless and is unique because it is the only natural substance that can exist in all three states of matter at the temperatures normally found on Earth! Water is usually a liquid, but when it reaches to 32° Fahrenheit (F), it freezes into ice. (Ice is the solid state of water.) When water reaches 212° F, it boils.
Water is essential for Human benefits like cooking, transportation etc. water affect our daily lives as the popular saying goes "we can do without water".
So we have two limestone beds, one of 550 million years old (well, the fossils are, but it suggests that the rock was created around the same area) and another that is 400 million years old. The first one is then older than the second - the correct answer is c!