Rachel's mother is 21 years older than she is. The ratio of their current ages is 2:1 . What will be the corresponding ratio of their ages 9 years from now?
A. 3:1
B. 17:7
C. 17:10
D. 7:5
E. 11:10
A. 3:1
B. 17:7
C. 17:10
D. 7:5
E. 11:10