Answer : 4. "34"
Explanation :

Answer: D) 34 Explanation: The given series follows the pattern that, 18, 97, 26, 91, ?, 83 => 18 + 8 = 26 => 97 - 8 = 91 => 26 + 8 = 34 => 91 - 8 = 83 Hence, the missing number is 34.