|A) only A alone is sufficient||B) only B alone is sufficient|
|C) both A and B are required||D) Cannot be answered|
For the given problem there are three possiblities.
Father's age can be = 36, 31, 29
Mother's age = 32, 27, 25
Son's age = 8, 3, 1.
By using only B it can be calculated.