People differ physically from one another because:
their alleles differ
their environments differ
their languages differ
their images differ

Which statement best describes a significant cause of world war ii? o a. the economic boom that followed world war i allowed countries to build up huge militaries. o b. the treaty of versailles, which ended world war i, left lasting resentments in many countries. o c. the rise of imperial states in asia caused european powers to unite for their common defense. o d. the league of nations encouraged european states to form secret military alliances.