This question seems like its too easy so i might have got it wrong.. but would't you just subtract 20 and 10 from 800 to get 770?
Answer:
The correct answer would be Y-chromosome analysis.
Y-chromosome analysis is technique used to search the parental line of a boy on his father's side.
Gender of a person is determined by
chromosome in humans. XX is present in females and XY is present in males.
Mother always passes X chromosome to her progeny but father passes both X and Y chromosomes. If X is passed from the father then the offspring will be a girl and if Y is passed from the father then the offspring will be the son.
The sons (F₂) of this son (F₁) will also bear the same Y chromosome as that of grand father (P).
Thus, Y chromosome always passes from father to son and hence, Y-chromosome analysis can help in identification of father of this young boy.
The answer is A.
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