During and after conditioning, the bell served as which of the following in Ivan Pavlov’s experiment with the dogs? a. unconditioned response
b. unconditioned stimulus
c. conditioned response
d. conditioned stimulus

 In Pavlov's experiment, the food was the unconditioned stimulus. An unconditioned response is an automatic response to a stimulus.

Explanation:

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the last statement is correct i.e.

when your heart is not pumping enough blood around your body because your heart is severely failing, you may need an artificial heart. an artificial heart is a mechanical device, about the size of an orange, that is connected to your heart or implanted in your chest to or replace a failing heart.

answer; (c) all the above