Which one of the following must be wrong about a DC motor?

A device that transforms electrical power into mechanical power is a DC motor. A current-carrying conductor experiences force when it is put in an external magnetic field, which is the basis for how a DC motor operates.

The formula for the force applied to the current-carrying conductor in newtons is

$F=BIL$

where 
B is the magnetic field applied to the conductor carrying the current, measured in tesla; 

I is the conductor's current, measured in amperes; 

L is the conductor's length, measured in meters.

The following components make up the DC motor:
(i) Armature
(ii) Spindle
(iii) Permanent Magnet
(iv) Split-ring commutators
(v) Brushes
(vi) Electric Source
Here is a schematic of a DC motor showing every component:

The following explains how these components function:
I Armature - The conductor that connects to the spindle and carries current is known as an armature. The armature rotates as a result of the force applied to it.
(ii) Spindle - A rotating component attached to the armature, the spindle. This component that extends from the motor is utilised to connect to the gadgets.
Permanent magnets are utilised to create the magnetic field (iii). They might be either electromagnetic or enduring.
(iv) Split-ring commutators - These are split rings that are attached to the armature and are used to shift the current's direction in order to guarantee that the armature makes a full circle.

(v) Brushes - Made of carbon, they are utilised to deliver current from the source to the split rings.
(vi) Electric Source - Split rings and bushes are used to deliver electricity to the armature. DC is the current's source.

Hence, the correct answer is option C.