According to article ii of the constitution, one of the president’s duties is to a. serve as commander in chief. b. create laws and interpret them. c. set up and manage the courts. d. serve in the house and senate.

Your answer would be to serve as the commander and chief. This is because the chief of something is always the leader. Say the chief of an Indian tribe. He is the leader. I hope this helps. I know I am probably too late but for later reference. :D
Good luck!