Azrael and Simon are training for track. Azrael trains at a rate of 6 miles every half hour. Simon trains at a rate of 2 miles every 15 minutes. What is the unit rate in mile per hour for each runner? *
A. Azrael = 12 miles per hour ; Simon = 8 miles per hour
B. Azrael = 8 miles per hour ; Simon = 12 miles per hour
C. Azrael = 6 miles per hour ; Simon = 2 miles per hour
D. Azrael =2 miles per hour ; Simon = 6 miles per hour