The correct option is (c) C-F actin - polymer of monomeric G-actin helically bound to each other.
Explanation:
A -Troponin, B -Tropomyosin, C- F-actin
Two filaments of protein tropomyosin run close to F-actins throughout its length.
A complex protein troponin is distributed at regular intervals oil the tropomyosin. In the resting state, a subunit of troponin masks the active binding sites for myosin on the actin filaments.
