Density (a) is the correct answer
<span>Scientists believe that differences in density cause hot, plastic-like rock in the asthenosphere to rise toward earth's surface. </span>
The answer to the question asked above is that according to wiki pedia BosWash<span> is a name coined by futurist George Fieraru in a 1967 essay describing a theoretical United States megalopolis extending from the metropolitan area of Boston to that of Washington, D.C.</span>
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