Profound social economic changes occurred
        
                    
             
        
        
        
Its called country regions......................................................................
        
             
        
        
        
Maybe this willl hellp"
Seismic waves are sent through the earth during earthquakes, and those
energy waves are what cause the ground to shake as they travel through
it.Seismic waves travel at different speeds when they pass through
different types of material, so by studying seismograms, scientists can
learn a lot about Earth's internal structure.Body waves are seismic
waves that travel through Earth's interior, or its 'body.' Surface waves
are seismic waves that travel through Earth's surface.Surface waves are
important, but they don't provide much information about what happens
below the surface. For this, we need to study body waves so that we can
see what Earth's 'body' is like.
There are two types of body waves, called P waves and S waves. P
stands for primary waves because these waves travel the fastest and are
detected first. S stands for secondary waves because these are slower
than P waves, arriving second on the seismogram.
        
                    
             
        
        
        
The correct answer is - d. colder and denser.
The main differences between the surface currents and deeper currents are the temperature and density, and that actually decides their position in the water, on the surface, or deeper.
The surface currents are warmer, and because they are warmer the molecules are much more loose, so the density is lower, which in return makes it easier, thus it is in the surface.
The deeper currents are colder, and because they are colder the molecules are much closer and more concentrated, so the density is higher, which means that they are heavier, thus fall deeper below the easier currents.