Me again , im sorry i keep asking but me

What is the function of the commutator in a dc motor? a. to spin the magnet b. to change direct current into alternating current c. to change alternating current into direct current d. to spin the wire coil

Which is not a source of noise pollution? a)airplanes b)acid rain c)machines d)cars

Each neuron shown in this figure innervates a group of muscle fibers. what is the term for a group of muscle fibers innervated by a single neuron?