Based on the residual plot shown, is a linear model appropriate for comparing tree age to basal area? Because the residuals are centered about zero, a linear model is appropriate.
Because the residual plot does not show a clear pattern, a linear model is appropriate.
Because the residual plot shows a random a scatter of points, a linear model is not appropriate. Because the residual plot does not appear linear, it is likely that tree age and basal area do not have a linear relationship.