Which of these are affected by Earth magnetic field A. a bar magnet hanging from a string
B. a magnetized needle floating in a dish of water
C. a piece of magnetic hanging from a string
D. all of the above​

What protects the lining of the stomach from acidic gastric juices?

Which conditions are necessary for natural selection to occur? select all of the answers that apply. a. inheritable adaptations vary among individuals. b. the population size is increasing. c. more individuals are born than can survive. d. fitness varies among individuals. e. the environment changes suddenly and drastically.

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