21. What does “opt out” mean with regards to Europe’s organ donation policy? A) They do not have permission to take your organs at any time.
B) You can sign up to donate at any time.
C) They take your organs unless someone says no at the time.
D) They take your organs only if you agree at the time.

Explain how fossils scientists make discoveries about the lives of organisms and about how environments have changed over time. plz hurry up it time

Students in biology are studying the macromolecules of life. they used a calorimeter to determine the calories in various types of food. once the lab was completed, the students ate the left over food samples. monica commented that in just 6 or 7 "chews" of the saltine, it was gone; nothing but a sticky paste in her mouth. elaborate on what happened chemically while chewing the saltine. include the macromolecules present.

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