PLEASE HELP HELP HELP What happens to the actin and myosin during a muscle contraction?

A. The actin filaments push against the myosin filaments, making the myosin filaments smaller.

B. The actin filaments are forced inward by the flexing of the muscle.

C. The myosin filaments remain in place as they pull the actin filaments inward.

D. The myosin filaments compress the actin filaments, making the actin filaments smaller.

Tooth enamel consists mainly of the mineral calcium hydroxyapatite, ca_10(po_4)_6(oh)_2. trace elements in teeth of archaeological specimens provide anthropologist with clues about diet and diseases of ancient people. students at hamline university measured strontium in enamel from extracted wisdom teeth by atomic absorption spectroscopy. solutions with a constant total volume of 10.0 ml contained 0.726 mg of dissolved tooth enamel plus variable concentrations of added sr. added sr find the concentration of sr in the 10 ml sample solution in parts per billion = ng/ml. find the concentration of sr in tooth enamel in parts per million = mu g/g.