Read the following passage and mark the letter A, B, C, or D on your answer sheet to indicate the correct answer to each of the questions from 26 to 30.

The natural environment is everything on Earth that isn't made by humans. This includes all living things, like plants and animals, as well as non-living things like rocks, water, and air. The natural environment is important because it provides us with the resources we need to survive, like food, water, and air. It also affects our economy by providing us with materials for building and manufacturing.

Humans have a big impact on the natural environment. We change landscapes by building cities and farms, and we pollute the air and water with chemicals and waste. These changes can harm the environment and make it harder for plants and animals to survive.

The environment is a complex system that includes many different parts. Scientists study the environment to understand how these parts work together and how human activities affect them. They also work to find ways to protect the environment and reduce the negative impacts of human activities.

The Environmental Protection Agency (EPA) is a government agency that works to protect human health and the environment. The EPA sets standards for air and water quality, and it works to reduce pollution. The EPA also works to protect endangered species and to restore damaged ecosystems.

Many organizations are working to protect the environment. These organizations use scientific evidence to develop solutions to environmental problems. They also work with governments and businesses to create policies and practices that protect the environment. These organizations believe that everyone has a role to play in protecting the environment.

What is the main idea of the passage?