Task: Question Answering
Input (English): Question: Capillary isotachophoresis (CITP) separates: 
 Options:  <1> Cations but can not separate anions. <2> Anions but can not separate cations. <3> Cations and anions simultaneously. <4> Cations and anions but not simultaneously. <5> Only neutral molecules.
Output (English): 4