The following represents sequences of different alleles of a gene found in a family represented by mother (allele1/ allele2), father (allele1/allele 2) and their two sons: Son1 (allele1/allele 2) and Son 2 (allele1/allele2). Further, a new mutation was observed in one of the alleles of the son, which is marked with a triangle.

Mother allele 1 :CAGCATAGTCATTCTGTCGTCATGGACTAG

Mother allele 2 :CAGCATTGTCATTCTGTCGTCATGGACTAG

Father allele 1 :CAGCATTGTCATTCTGTCGTCATGGGCTAG

Father allele 2 :CAGCTTAGTCATTCTGTCGTCATGGACTAG

Son 1 allele 1:CAGCATAGTCATTCTGTCGTCATGGACTAG

Son 1 allele 2:CAGCTTAGTCATTCTGTCCA $$\underset{\blacktriangle}{T}$$ GGACTAG

Son 2 allele 1:CAGCATTGTCATTCTGTCGTCATGGACTAG

Son 2 allele 2:CAGCTTAGTCATTCTGTCCAT $$\underset{\blacktriangle}{T}$$ GGACTAG

The following statements were made about the mutation:

A. The mutation arose in the germline of the father.
B. The mutation arose in the son.
C. The given DNA sequences are present on the X chromosome.
D. There is a possibility to use RFLP for tracking this variation.

Which one of the following options presents a combination of correct statements?

Correct option is B

Explanation-

Since:
Both sons have the same mutation.
The mutation is not found in father's somatic alleles, but both sons got it.
That means the mutation must have arisen in the father's germline (sperm DNA).
So, this is a germline mutation in the father, passed to both sons.

Statement A -The mutation arose in the germline of the father.     -  Correct.
The father doesn't carry the mutation in somatic DNA, but both sons inherited it → germline mutation.

Statement B - The mutation arose in the son    -   Incorrect
If it occurred in both sons independently, that’s very unlikely. More likely inherited from father's sperm.

Statement C -The given DNA sequences are present on the X chromosome. -  Incorrect / Cannot be concluded.
​Both sons have two alleles, which would not happen for X-linked genes in males (males are XY, only 1 X).
So, this gene is likely autosomal.

Statement D - There is a possibility to use RFLP for tracking this variation -  Correct.
If the mutation adds or removes a restriction site, it can be detected by Restriction Fragment Length Polymorphism (RFLP).

 Correct statement : A and D
This combination correctly identifies origin of mutation (father’s germline) and how to detect it (via RFLP).

Correct option is b - A and D.