This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: None, Subject name: Social & Preventive Medicine
All the following are examples of nominal scale except- 
Select and explain. 
A. Race, B. Sex, C. Iris color, D. Blood pressure
D: Blood pressure
Answer: D: Blood pressure 
Explanation: Nominal scale is used for qualitative data.

Blood pressure is quantitative data, which is used on the ratio scale.
Race, sex and Iris color are qualitative data.