Question

what type of rotary bits can cause a grinder to catch on rough material edges or shift around?
kerf
backing
abrasive
burr

Explanation:

A burr - type rotary bit has irregular or protruding edges which can easily catch on rough material edges and cause the grinder to shift around. Kerf refers to the width of the cut made by a cutting tool, backing is a support element, and abrasive bits are designed for grinding/smoothing and not typically the cause of catching in this way.

Answer:

D. burr