Michaelis Menten Hypothesis states that: (A) Rate of enzymatic reaction is independent of substrate concentration, (B) Rate of non enzymatic reaction is proportional to substrate concentration, (C) Km is the enzyme substrate complex association constant, (D) Enzyme substrate complex formation is essential in enzymatic reaction.
Answer is D. Michaelis-Menten Theory (Enzyme-Substrate Complex Theory) 
Enzyme combines with a substrate to form a transient Enzyme-Substrate Complex which immediately break into Enzyme and products.