Help me ASAP What happens to the actin and myosin during a muscle contraction?

•The actin filaments push against the myosin filaments, making the myosin filaments smaller

•The actin filaments are forced inward by the flexing of the muscle

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

•The myosin filaments compress the actin filaments, making the actin filaments smaller

Select the correct answer from each drop-down menu. in an experiment, dr. travis examined the effects of calcium intake on osteoporosis, a condition that causes an increased risk of bone fractures. the amount of calcium is variable. the risk of bone fractures .

Factors that can increase mutation rates a. high temps b. low temps c. food additives d. uv rays

Astudy by solloch and et. al., in 2017, gives the map above which shows the frequency of alleles with a ccr5-delta32 mutations over 87 different countries. this mutation deletes the presence of a co-receptor (ccr5) on the outside of human t-cells (lymphocytes). some viruses, such as the one responsible for the black death and human immunodeficiency virus (hiv), require this receptor for attachment to host cells during the infection process. the black death was an epidemic that passed over northern europe during the 14th century killing nearly 60% of europeans. according to this information, which explanation best explains why northern europeans show a greater immunity for hiv than some other parts of the world?