This is meiosis because we can see germ cells present, and the chromosome number is halved (typically) by the end of the process. This is nondisjunction because the sister chromatids/chromosomes are failing to separate properly during cytokinesis, causing improper amount of chromosomes in the germ cells. So on the left you have nondisjunction during meiosis II, because you have two cells with the proper amount of chromosomes after the first division. And on the right you have nondisjunction during meiosis I, because you have one cell with no chromosomes after the first division. The steps are as follows: 1 - Meiosis, 2 - Meiosis II, 3 - Fertilization, and 4 - Zygote (creation of).
