Which process is most suitable for creating a transparent colour effect over a lower layer without disturbing it?

Correct answer: Apply a thin transparent layer over a dry lower layer

The governing concept is glazing: placing a thin, transparent layer over a completely dry lower layer. Because the lower layer is dry and the upper film is controlled, the earlier colour remains visible without being lifted or muddied. A thick application reduces transparency, rewetting risks disturbing the base, and rubbing damages the separation between layers. Thus option B is the most suitable process.