A logger cuts down a tall tree while thinning a stand of longleaf pine trees. He cuts the tree trunk into several roughly cylindrical logs that can be carried. One log from near the top of the tree measures 32 inches around its circumference and 42 inches long. Another log cut from the lower part of the tree measures 64 inches around its circumference. If both logs have the same volume, about how long is the log cut from the lower part of the tree trunk?
A 7 inches
B 10.5 inches
C 14 inches
D 21 inches