In current classful addressing, there are 5 classes as shown in fig. 18.18 (p. 531 of the textbook). there are 5 classes with variable-length leading bits as follows:
class a: 0; class b: 10; class c: 110; class d: 1110; class e:
suppose that we wish to modify to accommodate 9 classes. what are 9 (variable-length) leading bits for them?

From the given information, we can understand that  

A->0->0 ones

B->10->1 two and 0 ones

C->110->1 four 1 two and 0 ones

D->1110->1 eight 1 four 1 two and 0 ones

E->1111-> 1 eight 1 four 1 two and 1 ones

We have change from the value of E and then accommodate 9 classes

E->11110->1 sixteen 1 eight 1 four 1 two 0 ones

F->111110->1 thirty two 1 sixteen 1 eight 1 four 1 two 0 ones

G->1111110-> 1 sixty four 1 thirty two 1 sixteen 1 eight 1 four 1 two 0 ones

H->11111110

I->111111111

the correct answer is: a.)it is never appropriate to use acronyms and emoticons in business communication.