Answer
The three generations and their ploidy levels are: embryo, new sporophyte generation, 2n; remaining embryo sac cells such as antipodals, gametophyte generation, n; all other tissues, old sporophyte generation, 2n.
Work Step by Step
To get to this answer, review of the alternation of generation lifecycle and see that the two generation there are n and 2n, with the remaining gametophyte material in figure 31.16 being the hardest to find (look for rounded maroon cells above and below the embryo).
