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: Microbiology
Positive Schick test indicates: 
Select and explain. 
A. Immune to diphtheria, B. Immune and hypersensitivity to diphtheria, C. Susceptible and hypersensitivity to diphtheria, D. Susceptible to diphtheria
D: Susceptible to diphtheria
Answer: D: Susceptible to diphtheria 
Explanation: Schick Test: The immune status of a person can be assessed by Schick's test. The test is performed by intradermal injection of 0.1 mL of purified standardized toxin. If the patient has no anti toxin, the toxin will cause inflammation at the site 4 to 7 days later. If no inflammation occurs, antitoxin is present and the patient is immune. A positive schick test indicates susceptible to diphtheria. Ref: Levinson W. (2012). Chapter 17. Gram-Positive Rods. In W. Levinson (Ed),Review of Medical Microbiology & Immunology, 12e.