When Salina was a young girl, a dog viciously attacked her as she was walking along a white picket fence. Since then, she displays intense fear of white picket fences. Salina is demonstrating:.1. a descriminative stimulus2. superstitious behavior3. stimulus descrimination4. a phobia5. spontaneous recovery

4. a phobia

Explanation:

Salina shows the signs of being phobic against the white picket fences because every-time she passes by the fence,her mind has created a picture of the incident which jogs her memory everytime shes walking by the fence.the fear can be very frustrating because most people find it difficult to understand what an individual is going through.

explanation:

with the profits from the european sales, merchants purchased europe's manufactured  goods, including tools and weapons. then the merchants shipped those manufactured  goods, along with the  american  sugar and rum, to west africa where they were bartered for  slaves.

the answer to your question is,

old stone age.

-mabel < 3