The concept of internal human stability which is also a central concept of human physiology which you're talking about/asking a question about would be homeostasis. By a homeostatis we're talking about a very narrow interval of functioning in which people function best and have optimal working efficiency.
Your answer is B
When the F1 generation exhibits both the parental characters, this is called codominance. The offspring will be a combination of both the parent. The ABO blood group system is one of the best examples of codominance. There are different types of red blood cells such as A, B, AB and O with or without the Rh factor.
Sure hope this helps