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.
1 reason is to kill disease in water
Sanitary landfill burial technology could help to reduce the amount of
waste going into a landfill
Explanation:
The land which is carefully designed into the top of the ground where trash is easily isolated. The main purpose of landfill is to keep It dry and care try to not come in contact with air. It is not like a compost pile.
This method is introduced by England in 1912. It is also called controlled tipping. It is about 1- or 3-meter feet. It is covered with clay.
