Answer:
The coach is a B. conditioned stimulus for Antonio's anxiety.
Step-by-step explanation:
In classical conditioning, a conditioned stimulus is a previously neutral stimulus who became as such by being paired with an unconditioned stimulus. It will activate a conditioned response in the future.
In this case, Antonio's coach has become a conditioned stimulus; his yelling was the unconditioned stimulus and Antonio's anxiety is his conditioned response to this.