Answer:
The correct answer is: 25 %
Explanation:
According to Mandel's law of inheritance, the dominant allele masks the expression of the recessive allele if present together. If a couple has 3 children with brown eyes. In a monohybrid cross, the ideal phenotypic ratio of the offsprings is 3: 1 or in other words, the dominant character chances to appear is 75% in phenotype.
So, by the law of dominance of monohybrid cross the chances of the fourth child to develop blue eyes is 25%.
Thus, the correct answer is : 25 %.