Francis enjoys spending time with his girlfriend, carla. carla will often eat a large number of grilled onions before spending time with francis. one day, francis walks by a hot dog stand and smells some fresh grilled onions. suddenly, francis has a great desire to see carla. what is the neutral stimulus (ns) in this scenario?
a. spending time with carla
b. a hot dog stand
c. grilled onions
d. spending time with francis