Final answer:
The number of cross-bridges formed between thick and thin filaments determines the amount of tension a muscle fiber can produce.
Step-by-step explanation:
The number of cross-bridges formed between actin and myosin determines the amount of tension a muscle fiber can produce. 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, resulting in more tension. Therefore, tension development reflects the number of cross-bridge interactions between thick and thin filaments.