Final answer:
A. A complex airplane has retractable landing gear, flaps, and a controllable pitch propeller. To act as pilot-in-command, you need an instrument rating. A complex airplane is defined by its features, and to act as pilot-in-command, you need an instrument rating.
Step-by-step explanation:
A complex airplane is defined by its features, which include retractable landing gear, flaps, and a controllable pitch propeller. These features contribute to the airplane's performance and handling characteristics. To act as pilot-in-command of a complex airplane, you need to have an instrument rating, which demonstrates your proficiency in operating the airplane's navigational instruments.