Answer:
B
Step-by-step explanation:
This person that is called on to testify during a trial must have the knowledge or skills in the field that is relevant to the case. A psychologist may be asked to serve as a consultant to an attorney or to a testifying psychologist. This can be used to determine if someone is being truthful or if they are being deceitful. They can be appointed by the court and they can sort through claims that are conflicting or if a conclusion cannot be reached. He is there to express his opinion based on his knowledge and education.