LIST I:	LIST II:
A. Turner's syndrome	I. An imbalance in X chromosome where two X from the ovum combine with a Y sperm
B. Fragile-X syndrome	II. An extra 21st chromosome
C. Down's syndrome	III. Ovum containing no X chromosome is fertilized by an X bearing sperm
D. Klinefelter syndrome	IV. The X chromosome is compressed or broken

Correct option is B

A. Turner's syndrome: This corresponds to "Ovum containing no X chromosome is fertilized by an X bearing sperm" (III). Turner's syndrome is a condition where a female is born with only one X chromosome instead of two, resulting from the ovum having no X chromosome, and the sperm contributing the only X chromosome.

B. Fragile-X syndrome: This corresponds to "The X chromosome is compressed or broken" (IV). Fragile-X syndrome is caused by an abnormality in the X chromosome, where a section of it becomes fragile or breaks, affecting mental development.

C. Down's syndrome: This corresponds to "An extra 21st chromosome" (II). Down's syndrome is a genetic disorder caused by an extra copy of chromosome 21, leading to developmental and intellectual delays.

D. Klinefelter syndrome: This corresponds to "An imbalance in X chromosome where two X from the ovum combine with a Y sperm" (I). Klinefelter syndrome occurs in males when they have an extra X chromosome, resulting in an XXY chromosomal pattern.

Thus, the correct answer is Option (2) A-III, B-IV, C-I, D-II.

Chromosomal and hereditary disorders are caused by abnormalities in chromosomes or genes. These disorders can be inherited or occur spontaneously due to mutations. Below is a breakdown of the types of chromosomal and hereditary disorders:

Information Booster : 

Chromosomal Disorders
These disorders result from changes in the number or structure of chromosomes. They are often caused by errors during cell division (meiosis or mitosis).

1. Numerical Chromosomal Abnormalities
Aneuploidy: Abnormal number of chromosomes (extra or missing chromosomes).
-Down Syndrome (Trisomy 21): Extra copy of chromosome 21.
-Edward Syndrome (Trisomy 18): Extra copy of chromosome 18.
-Patau Syndrome (Trisomy 13): Extra copy of chromosome 13.
-Turner Syndrome (Monosomy X): Females with only one X chromosome (45,X).
-Klinefelter Syndrome (47,XXY): Males with an extra X chromosome.
Polyploidy: Entire extra set of chromosomes (e.g., triploidy - 69 chromosomes).

2. Structural Chromosomal Abnormalities
Deletions: Part of a chromosome is missing.
-Example: Cri-du-chat Syndrome (deletion on chromosome 5).
Duplications: Part of a chromosome is duplicated.
-Example: Charcot-Marie-Tooth Disease (duplication on chromosome 17).
Translocations: Parts of chromosomes are swapped.
-Example: Philadelphia Chromosome (translocation between chromosomes 9 and 22, associated with leukemia).
Inversions: A segment of a chromosome is reversed.
Ring Chromosomes: Ends of a chromosome join to form a ring.
Isochromosomes: One arm of a chromosome is duplicated, and the other is lost.

Hereditary (Genetic) Disorders
These disorders are caused by mutations in genes and can be inherited from parents. They are classified based on the pattern of inheritance.
1. Single-Gene Disorders (Mendelian Disorders)
Autosomal Dominant:
-Only one copy of the mutated gene is needed to cause the disorder.
-Examples: Huntington’s Disease, Marfan Syndrome, Achondroplasia.
Autosomal Recessive:
-Two copies of the mutated gene are needed to cause the disorder.
-Examples: Cystic Fibrosis, Sickle Cell Anemia, Tay-Sachs Disease.
X-Linked Disorders:
-Mutations occur on the X chromosome.
-X-Linked Recessive: More common in males (e.g., Hemophilia, Duchenne Muscular Dystrophy).
-X-Linked Dominant: Rare (e.g., Rett Syndrome).