Answer:
D. in the past few decades, carbon dioxide levels have been falling.
Answer: Pedigree's in breeding dogs show the history of the dog and there traits. With a pedigree you can find the disease a dog may succumb to from it's ancestors or physical features.
With pedigree dog breeders can also find out whether a dog is purebred or not purebred.
Explanation:
Answer: chain link fence
Peptidoglycan could be found in high number on gram positive cell walls. The structure of peptidoglycan looks like a cross link which makes it sturdy, so rain coat would be false. It is not an impenetrable brick wall because it still allow some ion and food pass through it. Sugar candy coat sounds good but chain link fence would be better.
Dude i think it the calven cycle