How does the author convey the central idea selected in Part A? by providing scientific data on the physics and structure of the ride by providing scientific data on the physics and structure of the ride by pointing out how Pitzer was able to market the ride to the public by pointing out how Pitzer was able to market the ride to the public by describing riders' experiences on the ride as well as how the ride worked by describing riders' experiences on the ride as well as how the ride worked by presenting a firsthand account from a guest after riding the swing by presenting a firsthand account from a guest after riding the swing