Select the letter-cluster that can replace the question mark (?) in the following series. qDx, nHs, kLn, hPi, ?

EtD fTe eTd eSd

eTd

Explanation: qDx, nHs, kLn, hPi, ? The logic followed here is : q → (-3) → n → (-3) → k → (-3) → h → (-3) → e D → (+4) → H → (+4) → L → (+4) → P → (+4) → T x → (-5) → s → (-5) → n → (-5) → i → (-5) → d   So, the letter-cluster that replaces the (?) to complete the series is "eTd"