Understanding the Significance of pi_1 as the Sole Homotopic Functor

[quasar987]

My professor said that pi_1 is the only homotopic functor. I'm curious as to which degree should this affirmation be understood.

a) It has been proven that there cannot exist any other homotopic functor?

b) It is the only homotopic functor known to man.

or

c) There are others but they are not interesting.

 

[mathwonk]

sounds like nonsense to me. e.g. 2pi1 is surely another one. or pi(n),

or any homology functor.

 

[mathwonk]

it is the only non abelian homotopy group.