Based on the following code fragment, for extracting the word "know" from the sentence, what are the values of x and y respectively?

var a $=$ "You know the rules and so do I!";

var result $=$ a$.$substring$($x$,$ y$)$;

alert$($result$)$;

A$.$

x$=4,$ y$=7$

B$.$

x$=4,$ y$=8$

C$.$

x$=5,$ y$=8$

D$.$

x$=5,$ y$=9$