The 60° taper angle machined on work supported by lathe centers is most easily machined by the __________.

Correct Answer: Option D — compound rest

The compound rest is mounted on the cross slide and can be swiveled to any desired angle. It is the most efficient method for machining short, steep tapers, such as the 60-degree angle required for lathe centers, because it allows for precise manual control of the tool feed along the taper axis.