Err, I'm assuming that there were answer choices that you didn't post, but if not, Obsessive Compulsive Disorder? (OCD)
The answer is B!!!!!!!!!!!!!!!!!!
I dont know if this is correct, but I believe its Solar Systems. I might have to double check on that answer. but if its something else, I will tell you.
Answer:
heart blood vessels and blood
Answer:
Digestion
Explanation:
The breakdown of foods into forms that can be transported to cells and absorb into these cells(this process has two parts): Mechanical(breaks down large pieces of food into smaller ones) and Deglutition(swallowing).