Which of the following best indicates that the light reactions of photosynthesis have completed and that the calvin cycle has begun A) Electrons are transferred across the electron transport chain (ETC)on the thylakoid membrane.
B) ATP and NADPH accumulate in the stroma
C) An electrochemical gradient forms across the thylakoid membrane.
D) A high concentration of carbohydrates is found in the thylakoid lumen.