Question

which grinder accessory can be used to provide a stable surface for flexible sanding discs or buffing pads to rest against?
tool rest
backing pad
flip disc
anchor shield

Explanation:

A backing pad is used to provide a stable surface for flexible sanding discs or buffing pads to rest against. A tool rest is for supporting work - pieces, a flip - disc is a type of abrasive disc, and an anchor shield is not related to providing a surface for sanding or buffing pads.

Answer:

B. backing pad