Trisomy=3 chromosomes; 1 more than the required pair (2)
21=the type of chromosome
So, here we can eliminate A and B.
Now we have C and D.
I know that when sperm cell(s) simultaneously fertilize [an] egg, a class of identical twins will form. Therefore, we can eliminate D, leaving us with merely C. Henceforth, C is your final answer.
Answer:
Ventral
Explanation:
This is because when you want to dissect a pig, it's back is place on a dissecting tray and it's belly side is up which is the ventral side. With the ventral side, dissection will be easy and the major organs and systems can be observed easily as they will be rightly viewed because they are obvious and rightly placed at belly side up.
A. the distribution of sand on an ocean floor
Primary succession starts with bare rock which is broken down by either lichen or moss to make soil while secondary succession starts with developed soil