GAUSS8 1998 Problem 15

Michael picks three different digits from the set \{1,2,3,4,5\} and forms a mixed number by placing the digits in the spaces of \Box\frac{\Box}{\Box}. The fractional part of the mixed number must be less than 1. (For example, 4\frac23). What is the difference between the largest and smallest possible mixed number that can be formed?

Answer Choices
A. 4\frac35
B. 4\frac{9}{20}
C. 4\frac{3}{10}
D. 4\frac{4}{15}
E. 4\frac{7}{20}