I think it is D.... hope i'm right
<span>Activation energy refers to the amount of energy required by certain chemicals for them to have a reaction.
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Louder, because the sound would have a stronger pitch for the ear it is closer to
The muscular system is responsible for the movement of the human body. Attached to the bones of the skeletal system are about 700 named muscles that make up roughly half of a person's body weight. Each of these muscles is a discrete organ constructed of skeletal muscle tissue, blood vessels, tendons, and nerves.
