It Is Almost 35 Degrees Outside,and Ed Is on His

It is almost 35 degrees outside,and Ed is on his way to the supermarket to buy groceries.His air conditioner is broken,so he is hot and thirsty.Ed notices a billboard featuring an ice-cold Coca-Cola.Ed remembers that he is out of Coke.Once in the store,Ed heads straight for the soft-drink aisle and picks up a six-pack of Coke.
-Refer to Coca-Cola.In this case,what is the billboard ad?

A) a problem recognition
B) an external stimulus
C) an internal stimulus
D) a purchase outcome