A coded alphanumeric sequence has one missing item. Identify the option that correctly fills the blank.

AXD6, CZF12, EBH18, ?, IFL30

The correct option is GDJ24.

To find the missing term in the sequence AXD6, CZF12, EBH18, ?, IFL30, we analyze the pattern followed by each of the four components: the first letter, the second letter, the third letter, and the numerical value.

1. Pattern for the First Letter:
The first letters of the given terms are A, C, E, ?, I.
Converting these letters to their numerical positions in the alphabet:
A = 1, C = 3, E = 5, I = 9
Each letter advances by 2 positions:

$1+2=3$ (C)

$3+2=5$ (E)

$5+2=7$ (G)

$7+2=9$ (I)

Thus, the first letter of the missing term is G.

2. Pattern for the Second Letter:
The second letters of the terms are X, Z, B, ?, F.
Converting these letters to their positions in the alphabet (wrapping around from Z to A):
X = 24, Z = 26, B = 2 (or 28th letter), F = 6
Each letter advances by 2 positions:

$24+2=26$ (Z)

$26+2=28\Rightarrow 2$ (B)

$2+2=4$ (D)

$4+2=6$ (F)

Thus, the second letter of the missing term is D.

3. Pattern for the Third Letter:
The third letters of the terms are D, F, H, ?, L.
Converting these letters to their alphabetical positions:
D = 4, F = 6, H = 8, L = 12
Each letter advances by 2 positions:

$4+2=6$ (F)

$6+2=8$ (H)

$8+2=10$ (J)

$10+2=12$ (L)

Thus, the third letter of the missing term is J.

4. Pattern for the Number:
The numbers in the sequence are 6, 12, 18, ?, 30.
Each number increases by 6 in each step:

$6+6=12$

$12+6=18$

$18+6=24$

$24+6=30$

Thus, the numerical part of the missing term is 24.

Combining all components together gives the missing term: GDJ24.