Automation System
A stepping motor;

has a speed proportional to voltage input
can index positional movement.
None of these
has a commutator
is a good choice where continuous rotation is needed

ANSWER DOWNLOAD EXAMIANS APP

Automation System
Stepping motors:

do not require commutators
All of these
can run at varying speeds
can run both clockwise and counterclockwise
can be built to index different amounts by changing the pole configuration

ANSWER DOWNLOAD EXAMIANS APP