Joe has finished his first-aid course. He proves extremely helpful as a rescue worker.

A. Although Joe proves extremely helpful as a rescue worker, he hasn’t finished his first-aid course.

B. Having finished his first-aid course, Joe proves extremely helpful as a rescue worker.

C. Without finishing his first-aid course, Joe proves extremely helpful as a rescue worker.

D. However helpful Joe proves as a rescue worker, he hasn’t finished his first-aid course.