Explanation:

- Original Word: AEROPLANE

- Encoded Word: CCTMRJCLG

- For each letter in AEROPLANE, there's a corresponding letter in CCTMRJCLG.

To find the pattern:

- A (1) becomes C (3)

- E (5) becomes C (3)

- R (18) becomes T (20)

- O (15) becomes M (13)

- P (16) becomes R (18)

- L (12) becomes J (10)

- A (1) becomes C (3)

- N (14) becomes L (12)

- E (5) becomes G (7)

Check letter shifts between words:

- A->C, E->C: Shifts by -2 (A:1-2=C, C->E(-2)=C)

- R->T: Shifts by +2

- O->M: Shifts by -2

- And so on...

A pattern of alternating shifts.

For CHOPPER:

1. C + 2 = E

2. H - 2 = F

3. O + 2 = Q

4. P - 2 = N

5. P + 2 = R

6. E - 2 = C

7. R + 2 = T

Thus, CHOPPER becomes EFQNRCT

Answer is: Option 3: EFQNRCT