Task: Question Answering
Input (English): Question: The atomic mass of carbon is: 
 Options:  <1> The mass of 6.02.1023 carbon atoms, all of them being from the 12C isotope. <2> The mass of 6,022,103 carbon atoms, averaged according to the natural abundance of its isotopes. <3> The twelfth part of the mass of a carbon atom of the 12C isotope. <4> The sum of the mass of 6 protons, 6 neutrons and 6 electrons. <5> The mass of 12 protons.
Output (English): 2