The correct answer for the question that is being presented above is this one: "B. extra chromosome 21." Karyotypes can be studied to determine an organism’s chromosomal makeup and to detect genetic defects. Down syndrome is a genetic disorder that is also called trisomy 21. Trisomy 21 look like in a karyotype with <span>extra chromosome 21</span>
Explanation:
The development of the nervous system has so far, to a large extent, been considered in the context of biochemistry, molecular biology and genetics. However, there is growing evidence that many biological systems also integrate mechanical information when making decisions during differentiation, growth, proliferation, migration and general function
Protons, electrons and neutrons. Hope that helped :)