The correct answer is a.
Explanation
The image shows a portion of the earth's surface that has several physical characteristics marked with letters from A to E. The E refers to a cavern below the surface of the earth formed as a result of the formation of a sinkhole; D indicates a river that descends from the mountains and flows through a plain; the C refers to the slope of the mountain; the B indicates the snowy peak because it is the highest area of the mountain and it is covered with snow; A. refers to a sinkhole because it is a depression caused by a physical-chemical process that removes the bedrock below the surface. According to the previous definitions, the letter that corresponds to a sinkhole is A.
