The immune system is the bodies defense against invaders and is located in all body tissues with concentration in the mucosal surfaces and skin.
The three d's for group-living primates are detection, deterrence, and dilution. The primates are being preyed upon. Because of this, they developed defenses in order to protect themselves. The three d's of group-living primates are used in order to protect themselves to potential threat.
This is refered to as the chemical symbol. It is derived from the Latin name for the element which is why some elements like potassium (K) and sodium (N) have symbols different from their name on the periodic table.
C. Mutuality Relationship.
They have a mutual relationship by which both benefit.
When the hummingbird takes a sip off the daffodil, they are not sucking their strength out, they are simply sucking out pollen, which they then transfer to other flowers.
This process benefits both the plant and the bird.