Racial and Economic Inequalities
Privatization
Aging Infrastructure
i think it is 3a because when they are all together they are in like a clump so
Why Earth's inner core<span> has speed trap for </span>seismic waves<span>. </span>Earth<span> has multiple layers: the crust, the mantle, the liquid </span>outer core<span> and the </span>solid inner core<span>. Something is not quite right inside the </span>Earth's core<span>. When </span>seismic waves<span> from earthquakes ripple through its </span>solid<span> center, they hit a speed bump.</span>
