Answer: The correct option is B.
Step-by-step explanation:
Acoustic deals with the study of mechanical waves and the mediums through which they travel. It includes sound, infra sound, ultrasound and vibrations.
The mechanical wave is a wave which can travel through a material medium. It can travel through solid, liquid and gases. Sound is the mechanical vibrations of the particles of a gaseous medium.
Therefore, acoustic involves the study of mechanical waves and the mediums through which they travel.