At a small university, there are 1800 female students and 2000 male students. Which of the following expresses the ratio of female students to male students?
A.) 10 to 9
B.) 9/10
C.) 10/9
D.) 10 : 9
A.) 10 to 9
B.) 9/10
C.) 10/9
D.) 10 : 9