Task: Question Answering
Input (English): Question: The complexes of cobalt (III): 
 Options:  <1> They are all neutral or anionic. <2> They form the basis of our knowledge about the properties and reaction mechanisms of octahedral complexes. <3> They are usually flat-squares. <4> They present very fast substitution kinetics. <5> Almost all are prepared by replacing some ligands with others.
Output (English): 2