Answer : 1. "98"
Explanation :

Answer: A) 98 Explanation: The given number series is  3, 5, 8, 15, 28, 51, ? Here the pattern it follows is 3 3 + 2 = 5 ( add prime number less than 3 i.e, 2) 5 + 3 = 8 (3 is prime number less than 5) 8 + 7 = 15 (7 is prime number less than 8) 15 + 13 = 28 (13 is prime number less than 15) 28 + 23 = 51 (23 is prime number less than 28) 51 + 47 = 98 (47 is prime number less than 51)   Hence, the next number in the given number series is 98.