Each skeletal muscle is a discrete organ made up of hundreds or thousands of muscle fibers. although muscle fibers predominate, substantial amounts of connective tissue, blood vessels, and nerve fibers are also present. what happens during muscle contraction?

Which set of characteristics best describes sedimentary rock? a) largest type of rock, made of organic matter, hardest type of rock b) often contains layers, forms near sources of water, contains fossils c) least abundant type of rock, made of other rocks, made mostly of minerals d) most abundant type in earth's crust, made of magma/lava, contains no fossils