Select the letter-cluster from among the given options that can replace the question mark (?) in the following series. DAG, FCI, ?, JGM, LIOAGDJBIFLCHKEDHEKAnswer: D. HEK Read Explanation: Observe each position separately:First letters:D, F, H, J, L → increase by 2Second letters:A, C, E, G, I → increase by 2Third letters:G, I, K, M, O → increase by 2So the missing letter-cluster is:H E KSo, the answer is HEK. Read more in App