1) government regulation
2) advertisements for environmental protection
3) environmental education in schools
I think the government regulation is the most effective way to protect the environment.
First, the government can force people to protect the environment. (Bit awkward) To be specific, through by laws, the government can impose fines for to people who damage the environment in a way like dumping trashes into lake. This forceful method measure can actually have a big impact on people's actions.
Second, the government regulations can include a wide range of contents. There are many behaviors that can harm the environment. By documenting the detailed things about the environment in the law, the government can handle with various situations that can be detrimental to the environment effectively.
For these reasons, I think the government regulation is the best idea.
* 첫 번째 내용은 dumping trash이외의 예시를 보다 보여주시는 것이 좋습니다.
두 번째 부분에서는 various situation보다는, 다양한 분야에서의 환경오염을 사례를
나타내주시는 것이 좋겠습니다.