Answer:
a. thank the members of the orchestra and give them full credit for their hard work.
Step-by-step explanation:
David may have been the leader and helped improve the performance of the members of the orchestra. But, it will also be boastful and selfish of him if he was to take full credit for the effort and performance that was done as a team. Teamwork is all about "one for all and all for one" and as their leader, he should make sure he has what it takes to be a leader, being humble and giving. Just because he helped them in their practice doesn't make it the only cause of the success. The members too work hard on improving in their own ways. And that is exactly why David will thank the members of the orchestra and give them full credit for their hard work as they do work hard for the successful performance too.