What historically has had the greatest impact on the development of environmental policy?

The correct answer is C) efforts of conservationists.

What historically has had the greatest impact on the development of environmental policy is the efforts of conservationists.

The environmental policy has been the result of the effort and persistence of many conservationists and the work of the representatives that had approved laws to protect the environment. Local, state and the federal government have done many things in order to protect natural resources. Through the years, among the many pieces of legislation that protect the environment in the United States are the Clean Water Act, the Clean Air Act, and the Endangered Species Act.

The other options of the question were a) small-scale private environmental events, b) large-scale public environmental events, and d) none of the above.