Susan makes and sells rectangular quilts of different sizes. The width of each rectangular quilt is 3 units less than its length. The area of each quilt can be modeled by the function f(x)=x(x-3) , where x represents the length of the quilt. What is the reasonable domain of the function in the given context?
A. all integers
B. all integers greater than 0
C. all integers greater than 3
D. all integers greater than 3 and less than 0