The correct answer is A. fans.
Hysteresis motors are a type of electric motor that uses hysteresis to create torque. They are typically used in applications where low noise and vibration are required, such as fans.
Blower motors are a type of electric motor that uses a rotating impeller to move air. They are typically used in applications where high airflow is required, such as air conditioners and furnaces.
Sound equipment typically uses speakers, which are electromechanical devices that convert electrical signals into sound waves. Speakers are typically powered by amplifiers, which are electronic devices that increase the power of an electrical signal.
Mixer grinders are kitchen appliances that are used to mix and grind food. They typically have a rotating blade that is powered by an electric motor.
Hysteresis motors are not suitable for sound equipment or mixer grinders because they are not designed to handle the high levels of vibration and noise that these appliances produce.