Lines that are skew to EF are neither coplanar with EF, nor do they intersect EF. Examining the figure, we can determine that EF is a part of two separate planes, AEF and EFG.
By the definition of skew lines, we can rule out any line that runs along either of these planes.
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AB * & AE *
BF * & EH *
FG * & HG *
This leaves five potential skew lines. Let's mark these on the diagram.
Therefore, the lines that are skew to EF are: AD, BC, DH, DC, and CG.
However, only CG contains G.
