Which of the following letter-clusters will replace the question mark (?) in the given series?EFCD, GHEF, IJGH, ?, MNKL

Let's check the pattern for each position across the series:1st letter: E $\to$ G $\to$ I $\to$ ? $\to$ M$+2$ pattern: $\text{E}(5)+2=\text{G}(7)$, $\text{G}(7)+2=\text{I}(9)$, $\text{I}(9)+2=\mathbf{K}(11)$, $\text{K}(11)+2=\text{M}(13)$ 2nd letter: F $\to$ H $\to$ J $\to$ ? $\to$ N$+2$ pattern: $\text{F}(6)+2=\text{H}(8)$, $\text{H}(8)+2=\text{J}(10)$, $\text{J}(10)+2=\mathbf{L}(12)$, $\text{L}(12)+2=\text{N}(14)$ 3rd letter: C $\to$ E $\to$ G $\to$ ? $\to$ K$+2$ pattern: $\text{C}(3)+2=\text{E}(5)$, $\text{E}(5)+2=\text{G}(7)$, $\text{G}(7)+2=\mathbf{I}(9)$, $\text{I}(9)+2=\text{K}(11)$ 4th letter: D $\to$ F $\to$ H $\to$ ? $\to$ L$+2$ pattern: $\text{D}(4)+2=\text{F}(6)$, $\text{F}(6)+2=\text{H}(8)$, $\text{H}(8)+2=\mathbf{J}(10)$, $\text{J}(10)+2=\text{L}(12)$ The missing cluster is KLIJ.