Popular folklore suggests that “P” & “Q” stand for this in the phrase “Mind your P’s & Q’s”? 

a. Pigs & Quails
b. Pints & Quarts
c. Princesses & Queens
d. Pencil & Quills

"Mind Your P’s & Q’s” could stem from the practice of tallying a patron’s pints, or P’s, and quarts, or Q’s, on the board behind the bar in many British Pubs. If a customer didn’t pay attention and "mind his P's and Q's," the barkeep might add to his tab.