The correct answers are:
1. Paul Ehlrich argued that overpopulation was responsible for environmental problems - 1968.
Explanation: Stanford University Professor Paul R. Ehrlich and his wife, Anne Ehrlich wrote one of the best selling books - "The Population Bomb" in 1968 and argued that overpopulation is responsible for environmental problems.
2. The first national Earth Day marked the largest demonstration in American history. - 1970
Explanation: The first national Earth Day was founded by United States Senator Gaylord Nelson on April 22, 1970.
3. President Eisenhower asked the public health service to study ways to control air pollution- 1955.
Explanation: The Air Pollution Control Act of 1955 was signed by President Dwight D. Eisenhower to study ways to control pollution.
4. The Santa Barbara oil spill led to reforms in the energy industry - 1969
Explanation: The Santa Barbara oil spill occurred in January 1969 in the Santa Barbara led to reforms in energy industry.