Question

which is not a safe method for thawing food?
on a countertop overnight
as part of the cooking process
in a microwave
under cold running water

Explanation:

Thawing food on a countertop overnight is unsafe. Bacteria can multiply rapidly at room temperature. Thawing in the microwave, under cold running water, or as part of the cooking process are safer methods as they either keep the food at a temperature that inhibits bacterial growth (cold water) or quickly raise the temperature (microwave, cooking process).

Answer:

On a countertop overnight.