Tail feather length in birds is sometimes a sexually dimorp

Tail - feather length in birds is sometimes a sexually dimorphic trait. That is, the trait differs substantially for males and for females. Researchers studied the relationship between tail - feather length (measuring the R1 central tail feather) and weight in a sample of 20 male and 21 female longtailed finches raised in an aviary. We would like to use the observed least squares regression line between weight and tail ? feather length of males to predict the tail ? feather length of a male longtailed finches weighing 28g. Doing this

Solution

As we can see in the graph, scatter plot shows the regression line only till weight 21 g. By this graph it is not possible to predict the required value. So option D is correct.