Amuscle that is lengthening while it produces tension is performing a(n contraction.

I think the answer would be eccentric. Eccentric contraction would cause the muscles to lengthen as a response to a force that is much greater. The opposite of such is called concentric. Hope this answers the question. Have a nice day.

Because without physical activity, the body has extra "energy" if you will, and so when it is time for bed you are not tired, so you end up staying up all night. also there is probably an effect on your internal clock, which messes with your melatonin production which goes hand in hand with your sleep cycle

The answer will be d for the question