Which best contrasts electric doorbells and audio speakers?
a. doorbells involve rapid changes in the direction of current, and speakers do not. b. speakers involve rapid changes in the direction of current, and doorbells do not. c. doorbells require closed circuits in order to work, and speakers do not.
d. speakers require closed circuits in order to work, and doorbells do not.

B.Which best contrasts electric doorbells and audio speakers?

Explanation:

The answer is this because doorbells need a close circuit to make the sound they do speakers don't all they need are batteries and wires

the most logical answer would be a

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