**Core Concept**
Shick's test is a measure of cell-mediated immunity, specifically delayed-type hypersensitivity, which is an essential component of the immune response. It involves the intradermal injection of an antigen, such as tuberculin, to assess the body's ability to mount a cellular response against the antigen.

**Why the Correct Answer is Right**
The correct answer is related to the interpretation of Shick's test results. The test is used to assess the presence of a cell-mediated immune response, which is crucial for controlling infections such as tuberculosis. A positive result indicates that the individual has been previously exposed to the antigen and has developed a cell-mediated immune response.

**Why Each Wrong Option is Incorrect**
* **Option A:** This statement is true, as Shick's test is used to assess cell-mediated immunity.
* **Option B:** This statement is also true, as the test involves the intradermal injection of an antigen to elicit a cellular response.
* **Option C:** This statement is false, as Shick's test is not a measure of humoral immunity, which is mediated by antibodies.
* **Option D:** This statement is true, as a positive result indicates that the individual has been previously exposed to the antigen and has developed a cell-mediated immune response.

**Clinical Pearl / High-Yield Fact**
It is essential to remember that Shick's test is a measure of cell-mediated immunity, which is distinct from humoral immunity. This is a critical distinction, as cell-mediated immunity is often more effective in controlling infections such as tuberculosis.

**Correct Answer: C. Shick's test is not a measure of humoral immunity.**