【单选题】

Utilizing an airplane as intended by the manufacturer, combined with sound inspection and maintenance practices , forms the basis for assuring the airplane remains airworthy and safe to operatE.

A、The airworthiness and safe operation of an airplane is assured if it's used as its original design purpose, properly inspected and carefully maintaineD.
B、The manufacturer is intended to utilize an airplane with sound inspection and maintenance practices because that is the basis for assuring the airplane remains airworthy and safe to operatE.
C、The airplane is designed to be used as the manufacturer's intention. Users shall properly inspect the airplane and do sufficient maintenance to assure its airworthiness and operation safety.