Why does franklin devote a week to each of the virtues?
a: he is afraid he cannot work on more than one virtue at a time.

b: the teachings of pythagoras and socrates state that one week is all that is necessary to master a new moral habit

c: he thinks if he can strengthen one virtue through strict attention, he can retain that strength when he works on the rest.

d: he feels that total mastery of one virtue will bring more happiness than incomplete mastery of all virtues.