Which is NOT a danger of increased ultraviolet exposure at the Earth's surface?
A) The killing of microorganisms on the ocean's surface
B) The suppression of the human immune system
C) The increase of skin cancer in humans
D) The diminishing of yields in many crops
E) The significant warming of Earth's surface
Question 2
It is thought that the Earth's climate is being changed rapidly by ________.
A) human-caused releases of impurities
B) increased oxygen content
C) natural sources of change
D) dust from volcanoes
E) decreases in carbon dioxide