In trisomy 21, an error during meiosis results inthree copies of Chromosome 21, leading to developmental deficits.three copies of Chromosome 19.the normal two copies of Chromosome 21, and no developmental deficits.a point mutation.



Answer :

Explanation:

By definition, a trisomy is an aneuploidy in which a person has three copies of a chromosome instead of two. Therefore, a trisomy of chromosome 21 is an extra chromosome to the existing two copies of chromosome 21.

We can conclude that the correct answer is:

Answer:

Three copies of Chromosome 21, leading to developmental deficits.