Correct Answer - Option 3 : 36 years
Age of Rishabh = 10 years
If his mother is 20 years older than him.
So, age of his mother = (10 + 20) years
= 30 years
If his mother is 6 years younger than his father.
Age of his father = (30 + 6) years
= 36 years
Hence, ’36 years’ is the correct answer.