Positive Schick test indicates that the person is:: (A) Immune to diphtheria, (B) Hypersensitive to diphtheria, (C) Susceptible to diphtheria, (D) Susceptible and hypersensitive to diphtheria
Answer is C. Positive Schick reaction: 
This is characterized by a local inflammatory reaction that reaches maximum intensity in 4–7 days in the test arm and then reduces gradually. This indicates the absence of an immunity to C.diphtheriae.
Parija SC. Textbook of Microbiology & Immunology. Elsevier Health Sciences; 2014. Page:219