Choice "C" is correct. For a nongovernmental non-for-profit organization, a cash gift (with a stipulation that the principal be held for at least 20 years) should be recorded as a temporarily restricted asset (a 20-year spending restriction would be temporary because it can ultimately be satisfied).
Choice "a" is incorrect. The cash gift would be recorded as a temporarily, not permanently, restricted net asset.
Choice "d" is incorrect. The cash gift would be recorded as a temporarily restricted, not an unrestricted, asset.
Choice "b" is incorrect. The cash gift would be recorded as a temporarily restricted net asset, not a temporary liability. The term temporary liability is a distracter.