a.  The regression line for the husband's IQ from the wife's 
    IQ is the solid line, while the regression line for the  
    wife's IQ from the husband's IQ is the dotted line.  <p>

b.  The regression line for the husband's IQ from the wife's 
    IQ is the dotted line, while the regression line for the 
    wife's IQ from the husband's IQ is the solid line.  <p>

c.  The regression line for the husband's IQ from the wife's 
    IQ is the same as the regression line for the wife's IQ  
    from the husband's IQ, and both are equal to the solid   
    line.  <p>

d.  The regression line for the husband's IQ from the wife's 
    IQ is the same as the regression line for the wife's IQ  
    from the husband's IQ, and both are equal to the dotted  
    line.  <p>