The correct answer is "C. Study of the movement of air".
Aerodynamics is the study of the motion of air and its interaction with different objects. The term originated in the 17th century with the desire to improve the design of windmills and sailboats. Engineers dedicated to the design of cars and airplanes focus on this field of study in order to make designs that create the least friction while these vehicles are in motion. This is the reason behind the lack of sharp edges in airplanes and the growth in curvy designs of cars.