If We Wish to Use a Regression Line to Determine

Multiple Choice

If we wish to use a regression line to determine the effect of multiple treatment levels , why can't we just plot the average outcome for each treatment level and "connect the dots?"

A) Connecting the dots generally will not form a line.
B) Using averages for each treatment level will generally create bias.
C) This will cause us to have too few equations to solve for our unknown parameters.
D) We cannot use a regression line to measure the effects of multiple treatments.