Question 8 of 10 According to the law of conservation of energy, which statement must be true? A. There is only one form of energy. O B. Energy that is transformed is neither destroyed nor created. C. Energy can change only from nuclear to chemical. D. The total energy in a system can only increase over time. SUBMIT​

i believe it is "they are not used up by reactions" as the answer to your question, text me back if this is correct because i just learned this.

these muscles maintain the blood pressure in the vessels. the smooth muscles are innervated by nerves of the autonomic nervous system. when the muscles contract, they cause vasoconstriction of the vessels and increase blood pressure. when the muscles relax, they enable vasodilation of the   blood vessels hence reduce blood pressure.