Step 1: Understanding the Concept:
Analyze the shift in each individual letter position (first to first, second to second, etc.).
Step 2: Detailed Explanation:
acE $\to$ bdF:
a $(+1) \to$ b
c $(+1) \to$ d
E $(+1) \to$ F
The rule is a simple $+1$ shift for every letter, maintaining the case (lowercase/uppercase).
Step 3: Calculation:
Applying $+1$ to fbJ:
f $(+1) \to$ g
b $(+1) \to$ h
J $(+1) \to$ K
Result = ghK.
Step 4: Final Answer:
The missing term is ghK. Thus, the correct option is (b).