The region around Baotou, China currently provides more than 90% of the world’s supply of REEs despite China's having less than 40% of the world’s proven reserves (reflecting, in part, regulation regarding environmental issues pertaining to the refining process). The Problem 1 placemark shows a large artificial lake created to hold the slurry of liquid and solid waste products from the refining process (including radioactive thorium and uranium). Use the Polygon tab on the Ruler tool to measure the area (acres) of the tailings pile and lake (i. e., trace the boundary highlighted by the Problem 1 placemark). a. -2000 acres
b. ~40 acres
c. -640 acres