The most often used application of the term virtuosity applies to music - a virtuosic piece, a virtuosic musician etc. Thus the answer to this is b. Virtuosity means extreme technical proficiency in an area of music (though it can be applied to other things as well to show mastery of a skill - a virtuosic painter etc.)
I think it's C. Complementary
Binders used for watercolor paints commonly are natural gum or synthetic glycol,
tempera is usually glutinous material such as egg yolk
