The Variable (Pi) Used in the Shannon's Diversity Index (Or

The variable (pi) used in the Shannon's Diversity Index (or Shannon-Wiener Index) is

A) the number of trophic levels in the food web under study.
B) the number of connections between species in the food web under study.
C) the relative abundance value for each of the species in the community under study.
D) the relative evenness value for each of the species in the community under study.