In machine shop practice, a center gage is used for checking the angle of __________.

Correct Answer: Option B — 60° thread cutting tools

A center gage is specifically designed to verify the 60-degree angle of thread-cutting tools. By aligning the tool point with the gage's notches, the machinist ensures the tool is ground to the correct profile, which is critical for producing accurate, standard-compliant threads on bolts and studs.