Los angeles, san diego, and neighboring cities mutually support each other in their urban development and expansion. these cities have grown together into one continuous urban community, and together they are an example of a a. choropleth b. town c. megalopolis d. river valley civilization

Why is the huronian supergroup rock formation particularly interesting to scientists? because it looks like a cross-section of a giant, stone encyclopedia because it formed during the period when oxygen began to accumulate in the atmosphere because it contains unusually large amounts of oxygen and sulfur because it dramatically altered the planet's development when it first formed