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.)
In photography the background is the part of the overall scene. It's behind the main subject of the photograph. Proper design and use is crucial to photographic success. Recent trends minimise backgrounds, where possible, to focus on the main subject..•
