Anaphase I begins when the two chromosomes of each bivalent (tetrad) separate and start moving toward opposite poles of the cell as a result of the action of the spindle. Notice that in anaphase I the sister chromatids remain attached at their centromeres and move together toward the poles.
Explanation:
Chloroplast is the correct answer
It is a reduction of number of cells of their parent cell in half equal numbers.
