Task: Question Answering
Input (English): Question: A light-emitting diode: 
 Options:  <1> It is the same as a photovoltaic cell. <2> It is the inverse of a photovoltaic cell. <3> It is the same as a photovoltaic cell. <4> It is the inverse of a photovoltaic cell. <5> It is equivalent to a photochemical cell.
Output (English): 2