Please choose the correct answer to the question: Pepsin is an enzyme that acts in the stomach for protein digestion. Which of these is most likely the main role of pepsin in this metabolic reaction?

Answer1: to speed up the rate of reaction Answer2: to reduce the loss of energy as heat Answer3: to control the direction of the reaction Answer4: to protect the reaction from other chemicals

Answer format: answer1/answer2/answer3/answer4