**Core Concept**
The presence of short stature, wide-spaced nipples, and primary amenorrhoea in a female patient is highly suggestive of a disorder of sexual development, particularly Turner syndrome. This condition arises due to monosomy of the X chromosome, leading to impaired gonadal development and lack of estrogen production.

**Why the Correct Answer is Right**
45 XO (monosomy X) is the karyotype in Turner syndrome, which presents with short stature, webbed neck, broad nipples, and primary amenorrhoea due to the absence of a functional second X chromosome and underdeveloped ovaries. Estrogen deficiency results in incomplete female puberty and failure of uterine development. The phenotype is consistent with the clinical features described, and this is the most common karyotype associated with these signs.

**Why Each Wrong Option is Incorrect**
Option A: 47, XX+18 refers to a rare chromosomal duplication, not associated with the clinical features of Turner syndrome or primary amenorrhoea.
Option B: 46XXXY is associated with gynecomastia, ambiguous genitalia, and tall stature, not short stature or broad nipples.
Option C: 47, XXY (Klinefelter syndrome) presents with tall stature, gynecomastia, and infertility in males, not primary amenorrhoea in females.

**Clinical Pearl / High-Yield Fact**
In Turner syndrome, 45,XO is the most common karyotype, and all patients present with short stature and primary amenorrhoea. Early diagnosis is crucial for growth hormone therapy and estrogen replacement.

✓ Correct Answer: D. 45 XO