They transport oxygen to all the cells of the body
If we take the wolf as a species, then we can easily find its place and evolutionary path through this cladogram of chordates. The wolf is a vertebrate, so we start from vertebrae. It is an animal that has jaws and paired appendages. Continuing further up the cladogram we reach the development of lungs, and the wolfs have lungs for breathing. Then we come to the development of four limbs, and the wolfs have four limbs. Next comes the endothermy, meaning that the animal is able to regulate its own body temperature, thus it is warmblooded, and the wolfs are warmblooded animals. As last we come to the mammals, and the wolfs are part of the mammals, so we can classify them in that branch of the chordate cladogram.
A
B is wrong because mitochondria would likely absorb the stain even if it was dead.(And most cells that have been treated are dead anyway). C and D are just throwaway answers, you usually want to avoid the word "always" when drawing conclusions.
Decomposers do.
i wish that helped you