Task: Question Answering
Input (English): Question: The speed of the electron transport chain: 
 Options:  <1> It depends on the concentration of oxygen. <2> Increases when the concentration of ATP increases. <3> It is determined by the need for ATP. <4> It is independent of ADP phosphorylation. <5> It increases when the concentration of NADH and FADH2 rises. 6
Output (English): 3