The correct option is C Actomyosin complex
Cross-bridges can only form where thick and thin filaments overlap, allowing myosin to bind to actin. If more cross-bridges are formed, more myosin will pull on actin and more tension will be produced. Maximal tension occurs when thick and thin filaments overlap to the greatest degree within a sarcomere.
Cross bridge theory states that actin and myosin forms a protein complex called actomyosin complex, by the attachment of myosin head on the actin filament, thus forming a cross bridge between the two filaments.
So, the correct answer is 'actomyosin complex'.