Matching of Columns:

(A) AaBb × AaBb - (iii) 9:3:3:1
(B) AaBb × aabb - (ii) 3:1
(C) AaBB × AaBB - (i) 1:1:1:1
(D) Aa × aa - (iv) 1:1

Explanation:

The given question is based on the principles of Mendelian genetics. It requires the understanding of different types of genetic crosses and their outcomes.

Mendelian Genetics:

Mendelian genetics is the study of the principles of inheritance of traits from one generation to the next. It is based on the laws of segregation and independent assortment proposed by Gregor Mendel, the father of genetics.

Types of Genetic Crosses:

There are different types of genetic crosses, which are used to study the inheritance of traits in organisms. Some of the common types are:

- Monohybrid Cross: It involves the study of the inheritance of a single trait between two organisms.
- Dihybrid Cross: It involves the study of the inheritance of two different traits between two organisms.
- Test Cross: It involves the crossing of an organism with a homozygous recessive organism to determine the genotype of the former.
- Back Cross: It involves the crossing of an organism with its parent or an organism that is genetically similar to its parent.

Matching of Columns:

(A) AaBb × AaBb - (iii) 9:3:3:1

- This is a dihybrid cross between two heterozygous individuals.
- The ratio of the offspring is 9:3:3:1, which is the classic ratio observed in a dihybrid cross.
- This ratio is obtained by multiplying the individual ratios of two monohybrid crosses, which are 3:1 for each trait.

(B) AaBb × aabb - (ii) 3:1

- This is a monohybrid cross between two heterozygous individuals for one trait and homozygous recessive for the other trait.
- The ratio of the offspring is 3:1, which is the classic ratio observed in a monohybrid cross.

(C) AaBB × AaBB - (i) 1:1:1:1

- This is a monohybrid cross between two heterozygous individuals for one trait.
- The ratio of the offspring is 1:1:1:1, which indicates that all the four possible genotypes are equally likely to occur.

(D) Aa × aa - (iv) 1:1

- This is a monohybrid cross between a heterozygous individual and a homozygous recessive individual.
- The ratio of the offspring is 1:1, which indicates that half of the offspring will be heterozygous and half will be homozygous recessive.

Therefore, the correct matching of columns is:

(A) AaBb × AaBb - (iii) 9:3:3:1
(B) AaBb × aabb - (ii) 3:1
(C) AaBB × AaBB - (i) 1:1:1:1
(D) Aa × aa - (iv) 1:1

Correct option is 3