Question: With regard to pyrogens and biotechnological medicines, it is possible to say: 
 Options:  <1> They have no tendency to aggregate or form large units with high molecular weight. <2> Ion exchange chromatography procedures (using their positive charge) can reduce endotoxin levels. <3> Ion exchange chromatography procedures (using their negative charge) can reduce endotoxin levels. <4> Ion exchange chromatography procedures (regardless of their charge) can reduce endotoxin levels. <5> They are unstable under standard autoclaving conditions.
3