After a copper smelter begins operation, local downwind populations of plants begin to adapt to the resulting air pollution. Scientists document, for example, that the acid tolerance of several plant species has increased significantly in the polluted area. This is an example of

Adaptation.

Explanation:

Adaptation occurs when the acid tolerance of several plant species has increased significantly in the polluted area. The main reason for this tolerance is the change in the genetic makeup or mutation occurs in the cell due to the exposure of DNA to the chemicals of the environment that cause pollution. The plant adopt the environment by producing certain chemicals that cancel the effects of pollutants and as a result, the plant survive.

well for one plants are always the producer, so a is the answer. a wolf is more of the consumer(predator) and the deer is the prey so i know those two are out of the question. also mushrooms are fungi/fungus so a is the producer.