The theorist who credits people with the ability to learn through example and vicarious reinforcement is

A person's cognition, environment and behavior play important roles in learning new knowledge and skills. The psychologist Albert Bandura discovered the importance of behavioral models when he was working with patients with snake phobia. Bandura's social learning theory stresses the importance of observational learning, imitation and modeling. His theory integrates a continuous interaction  between behaviors, personal factors, including cognition. So, the theorist who credits people with the ability to learn through example and vicarious reinforcement is Bandura.

3. i would say one, but one is not prime nor composite.