1. Key unit of contraction composed of bundled parallel protein myofilaments 2. This part of muscle cell transmits AP.

i am not sure but i think you talk about myosin it is bind with ATP to do the contraction with actin

answer:

i believe the answer is d).

explanation:

i think this is because you are tearing apart the muscle, and then when you eat, the muscle re-heals, making itself even stronger.

edit: i put b) before but i meant to put d). sorry for the incorrect answer.

answer: all of the above

a. apply ice to the affected area.

b. administer tylenol (acetaminophen).

c. put a gate across the stairs.

d. apply knee and elbow protectors.