I would say because the respiratory system brings in the oxygen for the body and the circulatory system moves it throughout the body with the blood
The correct answer is option A. Energy cannot be created during an ordinary chemical reaction. There is no such thing as an ordinary chemical reaction. Energy cannot be created or destroyed this is according to the law of conservation of energy. It can only be transformed from one form to another form.
Answer: Balanced equation that is formed by combining these two half reactions is
.
Explanation:
A chemical equation which contains same number of atoms on both reactant and product side is called a balanced chemical equation.
For example, 

On cancelling the common species from both these half-reactions, the complete balanced equation will be as follows.
Thus, we can conclude that balanced equation that is formed by combining these two half reactions is
.
Answer:
it depends upon a his body which antigen is present
Explanation:
it depends on that person not on their parents