The true statement regarding screw gauges and shank is "the lower the gauge number, the larger the diameter of the shank.". Option D is the right choice.
A screw gauge measures the diameter of the shank, the unthreaded portion between the head and the threads. The gauge number indicates the thickness of the wire that the gauge can pass through.
Higher gauge number:
Smaller diameter of the shank: As the gauge number increases, the size of the hole in the gauge decreases, meaning it can only pass through a wire with a smaller diameter.
Shorter length of the shank: Not directly related to gauge number.
Lower gauge number:
Larger diameter of the shank: As the gauge number decreases, the hole in the gauge becomes larger, allowing thicker wires to pass through.
Longer length of the shank: Again, not directly related to gauge number.
Option D is the right choice.