The WBS helps the team of FOCUS! t is an excellent tool for communications and the basic for developing realistic estimates.How you can best describe?

Thank you for invitation. I seem D option is good answer.

Thanks for your question. Option D - the best describing for WBS as a tool for tracking of the project scope.

I will go with option D - Project Scope. WBS , apart from monitoring schedule, cost , resources etc., can also be used as an effective tool to control Project Scope & Scope Creep. 

it is best described as monitoring project scopes and results

Option (D) Project Scope ---------------

Yes, Option D is correct one