What causes the phases of the moon as observed from the earth?

a) filtering of the light from the moon due to the earth's atmosphere.
b) the tidal forces of the earth's oceans change the appearance of the moon.
c) change in distance of the moon from the earth as it orbits in an elliptical orbit.
d) the angle of light from the sun as it reflects off the moon and viewed from the earth's surface.

dna is made up of six smaller molecules -- a five carbon sugar called deoxyribose, a phosphate molecule and four different nitrogenous bases (adenine, thymine, cytosine and guanine).

the cladogram shown here shows similarities and differences among several classes of vertebrates. anatomically, the four have limb structure as their common ancestor. we might separate the mammals from the other three classes because they a) divergent; do not lay eggs b) identical; are warm-blooded c) varied; a four chambered heart d) homologous; have mammary glands

characteristics of hydrocarbons