Deborah Went to the Casino with $1,000 and Has Managed

Deborah went to the casino with $1,000 and has managed to win an additional $500. At this point, she has $1,500 in her possession; however, she separates this money into $1,000 that she stores in her purse, and the remaining $500, with which she continues to gamble. Deborah's behavior illustrates the phenomenon of

A) mental accounting.
B) superstitious behavior.
C) the gambler's fallacy.
D) the sunk cost fallacy.