I think it would be the thrid
Circulatory system:
--The circulatory system is also known as the cardiovascular system.
-- It is composed of the heart, blood, blood vessels and also includes the lungs.
The primary function of the circulatory system to distribute oxygen, nutrients, hormones and other gases to cells of the other body systems. It delivers all the necessary components needed for all the cell activities. Without the circulatory system, we would not be alive.
It is our blood that carries these necessary nutrients, hormones, and oxygen. All these components trigger certain processes that keep other organs functioning. It also plays a role in eliminating waste by carrying them to the necessary organs that will filter them out. Without a way to dispose of waste, the body will eventually die.
Answer:
Since boron only has two electron shells, it is about as capable of gaining electrons as it is of losing electrons, so it behaves as a metalloid. The other elements in this group have more electron shells, so it is much easier for them to lose their valence electrons and they behave like metals.
