Which one of the following condition in humans is correctly matched with its chromosomal abnormality/linkage?

Options

A. Klinefelter's syndrome-44 autosomes + XXY
B. Colour blindness - Y-linked
C. Erythroblastosis foetalis - X-linked
D. Down syndrome- 44 autosomes + XO

Explanation

To solve the question regarding the correct matching of a human condition with its chromosomal abnormality or linkage, we can analyze each option provided.

### Step-by-Step Solution:

1. **Identify the Conditions and Their Chromosomal Abnormalities**:
- We have four conditions to analyze: Klinefelter syndrome, colorblindness, erythroblastosis fetalis, and Down syndrome.

2. **Analyze Klinefelter Syndrome**:
- Klinefelter syndrome is characterized by the presence of an extra X chromosome in males, leading to a total of 47 chromosomes (44 autosomes + XXY). This is a correct match.

3. **Analyze Colorblindness**:
- Colorblindness is often incorrectly stated as a Y-linked condition. In reality, it is an X-linked recessive condition. Therefore, this option is incorrect.

4. **Analyze Erythroblastosis Fetalis**:
- Erythroblastosis fetalis is not caused by an X-linked defect. It occurs due to incompatibility between Rh factors (Rh positive and Rh negative). Hence, this option is also incorrect.

5. **Analyze Down Syndrome**:
- Down syndrome is caused by an extra copy of chromosome 21 (trisomy 21), not by having 44 autosomes plus an X chromosome. The description given matches Turner syndrome instead. Thus, this option is incorrect.

6. **Conclusion**:
- After analyzing all the options, the only correct match is Klinefelter syndrome with its chromosomal abnormality of XXY.

### Final Answer:
The correct condition matched with its chromosomal abnormality is **Klinefelter syndrome (XXY)**.