Task: Text Categorization
Input (English): Question: One of the following types of transport through membranes does NOT exist: 
 Options:  <0> Ion transport facilitated by ionophore (against electrochemical gradient). <1> Facilitated diffusion (in favor of electrochemical gradient) <2> Primary active transport (against electrochemical gradient). <3> Ionic channel (in favor of electrochemical gradient). <4> Simple diffusion (in favor of concentration gradient).
Output (English): pharmacology