Task: Text Categorization
Input (English): Question: In general, allosteric enzymes: 
 Options:  <0> They join the effectors in the active center. <1> They form covalent bonds with their negative effectors. <2> They originate hyperbolic curves of speed versus substrate concentration. <3> They change their conformation when they join the effectors. <4> They are irreversibly modified when they are inhibited.
Output (English): biology