The striated muscles have crosslinking proteins which help in muscle contraction. The thin filaments consist of actins and the thick filaments consist of myosin. Both actin and myosin are contractile proteins. The thin filaments also contain the contractile protein, called tropomyosin. It is a rod-shaped fibrous protein that form two helical strands, which are wrapped around the F-actin. An additional small globular protein molecule, called troponin, masks the active sites on the F-actin.
So, the correct answer is option A.