Final answer:
A person may have a common cold without a doctor's diagnosis, as it is self-diagnosable and can be treated with over-the-counter medications.
Step-by-step explanation:
Among the options provided, a person may have a common cold without a doctor's diagnosis. The common cold is widely recognized as a mild viral infection of the upper respiratory tract with symptoms like congestion, cough, and sometimes a low-grade fever. It is typically self-diagnosable and can be treated with over-the-counter cold medication to alleviate symptoms, although such medications do not diminish the intensity of the immune response. Unlike conditions like broken bones or allergies, which may require a doctor's diagnosis for proper treatment or identification, a common cold can often be self-managed.
A person may have allergies without a doctor's diagnosis. Allergies occur when the immune system reacts to harmless substances, such as pollen or pet dander. People can often identify their allergies based on a pattern of symptoms, such as sneezing, runny nose, or itchy eyes, without needing a formal diagnosis from a doctor.