Answer:
Iris
Step-by-step explanation:
Iris is the part of your body whose size never changes from the day we are born to our death.
It function is to allow limited amount of light passes through the lens.
It has pigmented melanin in it amount of which varies from person to person. When lights reaches the eye, it pass through the fiber of stromal cell and they reflected light from them is in color green, blue, olive, grey.
By this we observe different people have different color eye and by that we mean different color of iris.