The correct answer is: Aneuploidy occurs when one or more chromosomes are lost or gained relative to the normal euploid number. Polyploidy is the presence of three or more sets of chromosomes in the nucleus of an organism.
Aneuploidy is a phenomenon when there is the presence of an abnormal number of chromosomes in a cell (an extra or missing chromosome). Usually it appears as a result of improper cell division when chromosomes don’t separate (nondisjunction during mitosis or meiosis) and it can cause many genetic disorders.
Polyploidy refers to a state when there are more than two sets of chromosomes (one from mother one from father). Triploid (three sets of chromosomes) and tetraploid (four sets of chromosomes) chromosomes are examples of polyploidy. This phenomenon is most common in plants.