Answer: ATP NEEDED TO BREAK ACTIN-MYOSIN BONDS
Explanation: ATP (Adenosine Triphosphate) is the substance that allows energy to flow into the muscles,this energy helps the muscle to contract and work well so without this chemical (ATP), energy can't flow into the muscles and the muscle in-turn cannot function or contract.
When an individual dies,the body stiffens as a result of loss of Adenosine Triphosphate.
The muscles then stays in a contracted state until ATP becomes binded to myosin, thereafter, myosin and actin filaments will be released from one another.