Currently, most of the oil produced in the united states is produced by this method. a) drilling b) open pit mining c) heap-leach mining d) sub-surface mining

the answer would be b).

if he does not use open the compass the a width greater than half of po, he will not be able to find the midpoint of the line, without the midpoint of the line, he will not be able to bisect the line.   to find the midpoint of a line the circles drawn with a compass must either intersect or be touching.