How can local environmental changes have global effects?
a. organisms can move from one environment to another.
b. air and water move from region to region.
c. increased carbon dioxide in one location can cause increased temperatures in other locations.
d. all of the above are true.

The correct answer is - d. All of he above.

Local environmental changes do not stick to the place where they were made and only have effects on that particular place, but spread around and very often have a global effect. The increased levels of carbon dioxide at one place, doesn't mean that the temperatures will increase only there, but the carbon dioxide goes up in the atmosphere and influences the temperature on the whole planet. The polluted air and water are in constant move, so the pollution goes in different locations, like the example with Mongolia which has one of the most polluted air in the world because of the industry in China and the wind patters in the region.