An arrow is shot so that it hits the target above. Which of the following describes the method for calculating the probability of hitting the red region?
A area of white circle / (area of blue circle - area of yellow circle)
B. (area of blue circle - area of yellow circle) / area of white circle
C area of white circle / (area of red circle - area of yellow circle)
D. (area of red circle - area of yellow circle) / area of white circle