To find Mohan’s age on 31st December, 2000 we need to find his year of birth. From Statement A: There are multiple possibilities for the year of birth of Mohan-1953,1959,1971 etc. Hence, Statement I alone is insufficient to answer. From Statement B:There are multiple possibilities for the year of birth of Mohan’s son -1953,1971,1997 etc. Hence, Statement II alone is insufficient to answer. Combining Statement A and Statement B: Possible years of birth for Mohan and his son are ‘1959 and 1983’ or ‘1973 and 1997’. It is still not possible to get a unique solution. Hence the question cannot be answered even by using both the statements together.