Final answer:
You should call Emergency Medical Services (EMS) when in doubt for adults/adolescents, as prompt medical attention is critical in emergencies.
Step-by-step explanation:
For adults/adolescents, you should call/activate Emergency Medical Services (EMS) when in doubt about the severity of a person's condition. It is better to err on the side of caution and ensure that the person receives medical attention as quickly as possible, especially in situations that are potentially life-threatening. You do not need to consult a physician before calling for help in an emergency, nor wait for regular check-ups to address urgent health issues.