Which statement correctly describes an activity involved in muscle contraction?

a. myofibrils attach to z lines.

b. sarcomeres produce actin and myosin.

c. myosin heads attach to sites on actin filaments.

d. atp causes fascicles to contract muscle fibers.

the aswer is letter c

explanation:

b,bacteria convert nitrates

into nitrogen gas.

d,plants and animals take in

and use nitrogen compounds.

e,bacteria break down waste    

products and return nitrogen  

to the soil.

a,bacteria convert atmospheric

nitrogen to ammonia.

c,bacteria convert ammonia

to nitrites and nitrates.