Question: Why is it sometimes difficult to determine whether a "sign" is actually a "symptom" of illness? 1. Because symptoms are usually unrelated to underlying physiological conditions. 2. Because symptoms require expertise (e.g., a doctor's diagnosis based on signs) to verify. 3. Because symptoms are subjective, and therefore signs do not offer good information about illness. 4. Because symptoms are based on subjective interpration, so it is possible to misinterpret signs.