The answer is A. Lake.
A lake is a large body of water that is surrounded by land. A brook is a small stream of water. A stream is a larger body of water than a brook, but smaller than a river. A river is a large body of water that flows from one place to another.
Lakes are typically formed by glaciers, volcanoes, or other natural processes. They can also be created by humans, such as when a dam is built. Lakes are important for many reasons, including providing drinking water, supporting wildlife, and generating electricity.
Brooks are typically formed when rainwater flows over land. They are often found in forests and other areas with a lot of vegetation. Brooks are important for many reasons, including providing drinking water for animals, supporting aquatic life, and helping to regulate the flow of water in rivers.
Streams are typically formed when brooks join together. They are often found in valleys and other areas with a lot of slope. Streams are important for many reasons, including providing drinking water for humans and animals, supporting aquatic life, and helping to regulate the flow of water in rivers.
Rivers are typically formed when streams join together. They are often found in lowlands and other areas with a lot of flat land. Rivers are important for many reasons, including providing drinking water for humans and animals, supporting aquatic life, and helping to transport goods and people.