The karyotype can be used to diagnose a genetic disorder caused by a mutation in a single gene. A pedigree is useful to determine the inherited genetic disease occurrence in the prospective offspring at the “single gene locus of a person’s chromosomes”. Therefore, it is useful to determine the risk of developing a genetic disease in a child as per his/her family history.
The individual karyotype (number chromosomes or chromosomal model) study would depict individual’s genotype & chromosomal abnormalities caused by a mutation. The deletion or modification by a mutation with a “single gene locus” can be analyzed through karyotyping of genotypes. A Punnett square is a visual representation of crossing one or multiple genes to determine the probability of genotypic and phenotypic outcomes in the offspring.
Thus, the options (a), (c) and (d) are incorrect.
A pedigree is useful to determine the inherited genetic disease occurrence in the prospective offspring at the “single gene locus of a person’s chromosomes”.
Therefore, the correct option is – b. Pedigree.