The correct answer is Option (3) -(A)-(III), (B)-(I), (C)-(II), (D)-(IV)

(A) Metabolic Disorder (III) Phenylketonuria:

Phenylketonuria : This inborn error of metabolism is also inherited as the autosomal recessive trait. The affected individual lacks an enzyme that converts the amino acid phenylalanine into tyrosine. As a result of this phenylalanine is accumulated and converted into phenylpyruvic acid and other derivatives. Accumulation of these in brain results in mental retardation. These are also excreted through urine because of its poor absorption by kidney.

(B) Pedigree analysis (I) Family tree over generation:

Study of the family history about inheritance of a particular trait provides an alternative. Such an analysis of traits in a several of generations of a family is called the pedigree analysis. In the pedigree analysis the inheritance of a particular trait is represented in the family tree over generations

(C) Thalassemia (II) Blood disease:

Thalassemia : This is also an autosome-linked recessive blood disease transmitted from parents to the offspring when both the partners are unaffected carrier for the gene (or heterozygous). The defect could be due to either mutation or deletion which ultimately results in reduced rate of synthesis of one of the globin chains (α and β chains) that make up haemoglobin.

(D) Trisomy of 21st chromosome (IV) Down's Syndrome:

Down’s Syndrome : The cause of this genetic disorder is the presence of an additional copy of the chromosome number 21 (trisomy of 21). This disorderwas first described by Langdon Down (1866). The affected individual is short statured with small round head, furrowed tongue and partially open mouth.