My question didnt post so i amde a qr code to it

Why do we perceive objects as retaining their brightness under different lighting levels?

In many humans, exposing the skin to sunlight over prolonged periods of time results in the production of more pigment by the skin cells (tanning). this change in skin color provides evidence that -

Explain how paleontologists use trilobite fossils as index fossils for various geologic time periods.