Answer:

Explanation:
An element only has <u>one</u> type of atom and cannot be broken down by chemical means.
Let's analyze the answer choices.
1. This has two types of atoms, so it cannot be an element. It has more than one type of atom.
2. This has two types of atoms that are bonded together. It cannot be an element because there is more than one type of atom and the bonds can be broken.
3. This has one type of atoms, so it is an element.
Therefore the best answer choice is 3.
The correct answer is:
The principal cause of aneuploidy is chromosome nondisjunction during mitosis or meiosis. Polyploidy in nature can result either from the duplication of euploid chromosome sets from a single species or from the combining of chromosome sets from different species.
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 (chromosomes don’t separate) 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.
Answer:
the anwer is cell divides
Explanation:
Pregnancy. the body needs to gather nd make a new set of cells to build the baby