The answer is D. The ribs PROTECT the lungs and the heart. They allow you to move and they store minerals such as calcium. However it is the brain and the blood vessels that regulate the body temperature not the skeletal system.
Using the DNA to find out where the ivory comes from, Dr Wasser is able to work with law enforcement to know where to focus their protection measures. Having law enforcement in concentrated area that have been known to be poached can hopefully help prevent illegal poaching. Hope this helped :)
Nucleus is the correct choice, bacteria cells lack a Nucleus
Found in plants and algae.