Why does Joe begin calling Pip "Sir" as Pip gets better?

24. Why does Joe begin calling Pip "Sir" as Pip gets better?

A. Joe is acknowledging their different stations in life.

B. Joe thinks it will make Pip feel better.

C. Joe is really too hurt and angry to call Pip by his old name.

D. Joe is not sure that Pip recognizes him yet, and doesn't want Pip

to send him away.