Underutilization means something is not being used or explored to full potential. In that sense, the two pieces of evidence that support the idea that coal is underutilized are:
A.
only five percent of the power is used in traction on railway lines and the fact that ninety-five percent of it is lost;
C.
the present coal-mining practice does not extract more than half of the available coal and the fact that it leaves some parts of coal out of reach.
The options above offer us facts about the underutilization of coal. More than 90% of it is lost when used in railway lines and half of the coal available is not properly extracted. Options B and D, on the other hand, tell us about the importance of coal and the fact that we will run out of it soon. The underutilization mentioned in options A and C is certainly one of the main reasons for the exhaustion of coal.
