Task: Text Categorization
Input (English): Question: The alkaline error that occurs in glass electrodes for the average pH: 
 Options:  <0> It is due to the presence of an excessive concentration of protons that is replaced by sodium ions in the glass membrane. <1> Occurs at neutral pH due to the absence of protons. <2> It takes place at very alkaline pH, in which the sodium ion behaves as if it were a proton. <3> It appears as a consequence of the dehydration of the glass membrane. <4> It occurs when the electrode is introduced into pure water due to the dissolution of the sodium ions in the membrane.
Output (English): chemistry