Question

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

Explanation:

• Kert: Not a standard term related to rotary bits causing such issues.
• Backing: Refers to support material, not the cause of catching on edges.
• Burr: Burrs are rough, unwanted protrusions. When using a grinder, if there are burrs on the material (not the bit itself, but in the context of the question's phrasing, it's about the bit - perhaps a mis - phrasing, but burr - like bits can catch).
• Abrasive: Abrasive bits are for grinding, but the problem is about catching, not the general function.

Answer:

C. burr