Air pollution in us and canadian cities is caused mostly by a. clear-cutting forests for timber b. releasing emissions from vehicles and industry c. dumping runoff from farms into rivers d. harvesting minerals from mines

Most air pollution in United States and Canadian cities is caused by vehicle and industrial emissions. The correct option among all the options that are given in the question is the fourth option or option "D". This has led to increased amount of global warming. I hope the answer has helped you.

the images of war are haunting

the tariff was created to protect industry in the northern part of the united states. industries in the north were being driven out of business by imported goods that were priced at a low rate. the goal was to protect these industries   by taxing the goods.