Concept Class $C _ { 1 }$ Shows the Following Information for the Categorical Attribute Risk Factor

Concept class $C _ { 1 }$ shows the following information for the categorical attribute Risk Factor. Use this information to answer questions 9 and 10.

$\begin{array} { l l c }\underline{ \text { Attribute Name }} &\underline{ \text { Value }} &\underline{ \text { Frequency }} \\ \text { Risk factor } & \text { High Risk } & 25 \\ & \text { Medium Risk } & 10 \\ & \text { Low Risk } & 5 \end{array}$
-Suppose that the predictiveness score for risk factor = medium risk is 0.50. How many domain instances have a value of medium risk for the risk factor attribute?

A) 10
B) 20
C) 30
D) 40