Deforestation, acid rain, and the greenhouse effect are major world problems that indicate a need for
1.cooperation between nations to reduce pollution and environmental destruction
2. the development of mass transit systems in developing nations
3. an increase in the worldwide production of oil
4. a reduction in crop production in some ares of the world

the only logical answer here would be: 1: cooperation between nations to reduce pollution and environmental destruction

reason:

in the question you asked you mentioned acid rain, deforestation, and the greenhouse effect as being problems.

In answer 2. we are dealing with transit systems that can lead to more air pollution,  if the transit system emits exhaust it can lead to acid rain.

In response 3. we are dealing with oil, accidents such as oil spills can reek havoc on animal life in the waters and disturb the natural habitat for other animals, such as birds that eat fish. the burning of oil can also cause air pollution. 

As for response 4.  we are dealing with crops, farmers use equipment that burns gas or oil which goes into the atmosphere and one could say that it causes global warming, disrupted the natural habitat for animals that used to live on the land before it was converted to farmland.

Just an FYI, my responses have nothing to do with how I truly feel about the topic in which is being discussed in your question.

Hopefully this helped and good luck.

what is the answer