those would be myofibrils
If i would have to make an educated guess, i would say C.
Organisms can be made up of many<em> </em><u>cells</u>, which could be arranged into <u>tissues</u> which can make up<u> organs</u>, organs can be part of a(n)<u> system</u>. These are........i don't really know after this since you didn't give a lot to work with and i'm not even sure if this is right or not lol.
