How can tight muscles result in back pain?
a.
they contain sensitive nerves that become painful when tight.
b.
they can constrict the nerves in the spinal column.
c.
tight muscles stretch surrounding tissues and organs.
d.
they improve posture, which results in back pain.

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delegated (sometimes called enumerated or expressed) powers are specifically granted to the federal government in article i, section 8 of the constitution. this includes the power to coin money, to regulate commerce, to declare war, to raise and maintain armed forces, and to establish a post office.