Which of these is an environmental cost of tar sands extraction? A. Mine collapse B. Pollution C. Acid rain D. Shale deposits

I'm 90% sure the answer is B) Pollution.

Tars sands or oil sands are extracted like crude oil from the ground, but involves a larger processing procedures like extraction, upgrading and processing of bitumen from the oil sand. Like the extraction of any kind of fossil fuel involves environmental costs, this process also includes a higher environmental cost.

The extraction process of tar sands emits a higher rate of greenhouse gases into the atmosphere than the conventional oil extraction procedure. The greenhouse gases converts into acid clouds when they get oxidized in the atmosphere and returns to earth as acid rain. Hence acid rain is one of the environmental cost of tar sands extraction