**Core Concept**
Schick's test is a method used to determine an individual's susceptibility to diphtheria, a bacterial infection caused by Corynebacterium diphtheriae. The test involves injecting a small amount of diphtheria toxin into the skin of the individual, and observing the reaction.

**Why the Correct Answer is Right**
A positive Schick test result indicates that the individual is not immune to diphtheria and will develop a localized skin reaction, typically an erythematous (red) reaction, at the site of injection. This occurs because the individual lacks sufficient antibodies to neutralize the diphtheria toxin. On the other hand, a negative test result indicates that the individual is immune to diphtheria, meaning they have sufficient antibodies to neutralize the toxin and prevent a reaction. A positive test does not mean that the person is immune to hypersensitivity diphtheria, but rather that they are susceptible to the toxin.

**Why Each Wrong Option is Incorrect**
**Option A:** This statement is true, as an erythematous reaction in both arms indicates either a positive test result or a false negative result due to an inadequate dose of toxin.
**Option C:** This statement is true, as diphtheria antitoxin is indeed given intradermally in the Schick test to determine the individual's immune status.
**Option D:** This statement is incorrect, as option B is the false statement.

**Clinical Pearl / High-Yield Fact**
It is essential to remember that a positive Schick test result is not a guarantee of future diphtheria infection, but rather an indication of susceptibility. Vaccination against diphtheria is the most effective way to prevent the disease.

✓ Correct Answer: B. Positive test means that person is immune to hypersensitivity diphtheria