Okay, let's tackle this question. The patient is a 22-year-old female with primary amenorrhea, short stature, widely spaced nipples, and a webbed neck. The question is about the karyotype. First, I need to recall the classic presentation of Turner syndrome. Turner syndrome is caused by a 45,X karyotype, which is a monosomy of the X chromosome. The symptoms mentioned here—primary amenorrhea, short stature, webbed neck, and widely spaced nipples—are all classic signs of Turner syndrome.

Wait, the options aren't listed here, but the correct answer is given as option B. Let me think about the other possibilities. Other karyotypes that might be confused with Turner syndrome could include Klinefelter syndrome (47,XXY), which affects males and presents with tall stature, infertility, etc. Down syndrome (47,XX+21 or XY+21) has different features like facial dysmorphia and intellectual disability. Edwards syndrome is trisomy 18, which is more severe and has different manifestations. So the key here is the female phenotype with X monosomy.

The core concept here is Turner syndrome's karyotype and its clinical features. The correct answer is 45,X. The other options would be other chromosomal abnormalities. The clinical pearl is that Turner syndrome presents with the specific features mentioned and a 45,X karyotype. The student should remember that primary amenorrhea with these physical signs is a classic presentation of Turner syndrome.

**Core Concept**
This question tests recognition of Turner syndrome, a chromosomal disorder caused by monosomy of the X chromosome (45,X), leading to ovarian dysgenesis and characteristic physical features. Clinical features include short stature, webbed neck, and primary amenorrhea.

**Why the Correct Answer is Right**
Turner syndrome (45,X karyotype) presents with primary amenorrhea due to gonadal dysgenesis, short stature from growth hormone deficiency, and lymphatic abnormalities causing webbed neck and shield-shaped chest with widely spaced nipples. The absence of secondary sexual characteristics confirms ovarian failure.

**Why Each Wrong Option is Incorrect**
**Option A:** 47,XXY (Klinefelter syndrome) causes male hypogonadism, tall stature, and gynecomastia, not webbed neck or amenorrhea.
**Option C:** Trisomy 21 (Down syndrome) presents with intellectual disability, facial dysmorphia, and congenital heart defects, not ovarian failure.
**Option D:** Trisomy 18 (Edwards syndrome) is lethal in infancy with severe congenital anomalies, not a chronic phenotype.

**Clinical Pearl / High-Yield Fact**
Turner syndrome is the only chromosomal disorder with a 45,X karyotype. Remember the **"5 Ws"**: Webbed neck, Widely spaced nipples, Wasting of the skin, Weak or absent uterus, and Women with primary amenorrhea. Early diagnosis allows growth hormone and estrogen replacement.

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

✓ Correct Answer: C. 45, XO