All of the Following Except One Are Among the Strategies

All of the following except one are among the strategies that children adopt to delay gratification. Which is NOT one of their strategies?

A) Children attempt to bargain with other children present for a more desirable object as a means of delaying "consumption" of the object that they currently possess.
B) covering up the preferred objects (M&Ms) or leaving them in the open
C) thinking of the preferred object abstractly (M&Ms are buttons not "yummy") or concretely
D) thinking of the task at hand or the future enjoyability of the preferred object