65. Which of the following statements regarding Michaelis-Menten kinetic analyses of enzyme action are correct? ① The total enzyme concentration studied at each substrate concentration is fixed in analysis of enzyme kinetics. ② Formation of enzyme-substrate complex does not appreciably decrease the concentration of substrate. ③ cat reduces with competitive inhibition. ④ Maximal velocity is reached when the enzyme-substrate complex is equal to the total concentration of enzyme present. ⑤ The initial reaction velocity should be measured because most of the substrate has not been converted to product. (A) ①②③④ (B) ①②③⑤ (C) ①②④⑤ (D) ②③④⑤ (E) ①③④⑤