Direction: In the following questions, read the passage carefully and choose the best answer to each question out of the four alternatives.
PASSAGE
The destructive process of Mountain Top Removal mining (MTR) has caused permanent damage to Appalachia. Although the law requires that mining companies restore the mountaintops after the mining has been completed, the 1.5 million acres of mountains that have already been removed cannot be re-grown, re-built, or replaced. The companies do secure the rock formations to prevent erosion and landslides, but their efforts cannot recreate the once beautiful mountain landscape. Furthermore, while companies are usually vigilant about securing the rock formations, they seem less interested in restoring the native vegetation. MTR operations clear enormous tracts of forest. Environmental hazards are not only created in preparing a mountaintop for mining, they also continue once the coal has been extracted. After the blast, the excess mountaintop — which miners refer to as “overburden” — is usually dumped into nearby valleys or streams. The overburden contains a variety of toxic substances, including explosive residue, silica and coal dust.