Help!I am stuck in this question and need some explanation.?

The cells of the organism have 2 copies of each chromosome. When it forms a gamete, the gamete includes HALF those chromosomes, because the gamete is the cell that needs to combine with another cell to reproduce. Therefore, when it combines, the resulting organism will again have two copies of each chromosome.
So, you're looking for the diagram that includes HALF the contents of the original diagram.