DC motor is used to convert the electrical energy into the mechanical energy.
DC motor uses a brush and commutator to operate. The function of the commutator is to reverse the direction of electric current at every point. It also connects the power supply to the rotating coils with the help of brushes.
Brushes are used to carry current to the armature of the coil. Due to this, a magnetic field is created so that the motor runs. There are two brushes. One brush is connected to the switch and another brush is connected to the commutator.
Hence, a DC motor uses a brush and commutator to operate.
I think its D. because Tea during a cold workout isnt safe at all. Drinking tea while working out adds weight and you just simply dont need tea when working out.. Hope this helps man :)