What effect may occur when a small drop of colour is added to a wet watercolour surface?

Correct answer: The colour may spread softly outward

The governing concept is the wet-on-wet method. Because the paper and surrounding paint contain water, a newly added drop of pigment is carried outward by moisture, producing a soft spread, diffused boundary, or bloom-like mark. The exact result depends on how wet the surface is and how concentrated the drop is. Thus option A is correct. Sharp fixed edges are more characteristic of paint applied to a dry surface, not option B.