On justification questions, we want to guarantee the conclusion, so we should choose a principle that is very strong. In this case, we want to confirm that Germany should aid these countries. Which principle will guarantee this result?
The difference between B & D is a reversal of sufficient and necessary conditions. Alone has the capacity = AHC Should exercise capacity = SEC
B. AHC - - - - - - - -> SEC
D. SEC - - - - - - -> AHC
We already know that Germany has the capacity to help these troubled countries. If we choose principle B, it follows logically that Germany should exercise this capacity. The sufficient condition guarantees the necessary.
If we were to choose D, then we cannot confirm that Germany should help. The necessary condition does not guarantee the sufficient condition.
If this doesn't make any sense, I would go back and watch the video lesson on sufficient & necessary.