The correct answer to the question is - A) Object's kinetic energy is transformed into mainly heat energy.
EXPLANATION:
The friction is the opposing force which acts tangentially between two surfaces when there is a relative velocity between them.
As per the question, the moving object comes to rest after the application of frictional force.
Initially the object is in motion.Hence, the energy possessed by the moving object is kinetic energy.
When frictional force is applied on the moving object, the kinetic energy of the moving object will be converted into mainly heat energy. It is due to the fact that friction causes heat production between two surfaces in contact.
Hence, correct option will be that the object's kinetic energy is transformed into mainly heat energy.
