On a clear day, the sky appears to be more blue toward the zenith (overhead) than it does toward the horizon. This occurs because
A) the atmosphere is denser higher up than it is at the earth's surface.
B) the temperature of the upper atmosphere is higher than it is at the earth's surface.
C) the sunlight travels over a longer path at the horizon, resulting in more absorption.
D) the atmosphere is more reddish over the ocean.
Question 2
Seafloor spreading on the Earth is the process by which
A) volcanic material flows from the deep interior to produce volcanic islands
B) dense material sank while lighter material rose to the surface during the early geological history
C) molten lava oozes out between two tectonic plates that are slowly moving apart
D) oceanic crust sinks below continental crust at a tectonic plate boundary