The researchers found evidence of gene flow between some, but not all, pairs of populations. In the grid below, a "+" indicates a pair of populations in which direct gene flow was detected, and a "-" indicates a pair that showed no evidence of direct gene flow.The researchers discovered that the 12 populations could be organized into 3 distinct species. Populations A, B, and C each belong to a different species. Use the data in the grid to sort each population to the species to which it belongs.