Answer:
The conditioned stimulus is the staircase.
Explanation:
In classical conditioning, a conditioned stimulus (the staircase) is associated with an unrelated consequence called unconditioned stimulus (the screaming). This produces a reaction known as conditioned response (fear).
It's important to realise that any stimulus can become conditioned. In the example, if Shane's mother had screamed at the sight of a dog, the baby would probably be afraid of dogs.
