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

Megalopolis. This term refers to neighboring cities that have organically grown their borders over time so that it is difficult to find out where one city ends and the other begins. The only condition for this term to be awarded to a chain of cities is that each of the member cities must be a metropolis in its individual capacity.

Argon, carbon-14, and carbon-12