Ginger walks at 4\:km/h and runs at 6\:km/h. She saves 3\frac34 minutes by running instead of walking from her home to her school. What is the distance, in kilometres, from her home to her school?
Answer Choices
A. 7\frac12
B. 3\frac34
C. 1\frac78
D. 1\frac14
E. \frac34