:1.   Imagine a scatter diagram, with its regression line
passing through it.  Now add another point to the scatter
diagram.  Suppose this new point lies on the regression line.
Then <p>

a.  The regression line of the new scatter diagram is the    
    same as the one for the original scatter diagram.  <p>

b.  The regression line of the new scatter diagram cannot    
    possibly be the same as the one for the original 
        scatter diagram. <p>

c.  In order to tell whether or not the regression line for  
    the new scatter diagram is the same as the one for the   
    original scatter diagram, you need more information about 
    the original scatter diagram and the point which is added 
    to it.  <p>