Viewing the Results in the Following Scatterplot, for the 11 $\ge$

Viewing the results in the following scatterplot, for the 11 cases to the left subset (Age < 40) , two belong to Class 1 and nine belong to Class 0. In the right subset (Age ? 40) three belong to Class 1 and one belong to Class 0. What is the Index score for the two subsets?

A) (Age < 40) = 0.3636; (Age $\ge$ 40) = 0.50
B) (Age < 40) = 0.20; (Age $\ge$ 40) = 0.25
C) (Age < 40) = 0.298; (Age $\ge$ 40) = 0.375
D) (Age < 40) = 0.375; (Age $\ge$ 40) = 0.298