Answer:
A. the ability to do something well without wasted time or effort. Productivity is the act of being able to produce/do multiple tasks at once efficiently without wasting time. You would think this may make option D correct, but that's not the case. Productivity is more than just doing a task, it can also be producing a certain thing at a given time without wasting the effort put into that task. That said, option A would make the most sense here.
Hope this helps!