**Core Concept**
Androgen Insensitivity Syndrome (AIS) is a genetic condition where individuals with a 46,XY karyotype are resistant to male hormones, androgen, resulting in the development of female external genitalia despite having testes. This condition is caused by mutations in the androgen receptor (AR) gene.

**Why the Correct Answer is Right**
The correct answer is **46,XY**. This is because individuals with AIS have a normal male karyotype, but their cells are unable to respond to androgens due to the mutated androgen receptor. As a result, they develop female external genitalia and are phenotypically female. The presence of testes in these individuals is a result of the SRY gene on the Y chromosome, which triggers testis development.

**Why Each Wrong Option is Incorrect**
**Option A:** 46,XX - This karyotype is associated with normal female development and is not characteristic of AIS.
**Option B:** 47,XXY - This karyotype is associated with Klinefelter syndrome, a different genetic condition that affects male development.
**Option C:** 45,X - This karyotype is associated with Turner syndrome, a genetic condition that affects female development.
**Option D:** 47,XXX - This karyotype is associated with a rare genetic condition that affects female development.

**Clinical Pearl / High-Yield Fact**
Androgen Insensitivity Syndrome is a classic example of a condition where the genotype (46,XY) does not match the phenotype (female external genitalia). This highlights the importance of genetic testing in diagnosing conditions where the clinical presentation does not match the expected karyotype.

**Correct Answer: C. 45,X.**