During the course of the formation of a parasite/host ...

[penza]

During the course of the formation of a parasite/host relationship, a critical first step in this evolution would be
A) changing the behavior of the host or intermediate host.
B) developing asexual reproduction.
C) deriving nourishment without killing the host.
D) starting as an ectoparasite and then later becoming an endoparasite.
E) utilizing heterotropic nutrition during infection and autotrophic nutrition during dormancy.

[plus1]

I recall doing this last year, it's C, bye bye!

[penza]

Thanks for assisting, your answer was right!