Explanation:

- In the given code, each letter is replaced with the previous letter in the alphabet. For example: S becomes R, and C becomes B.

- Numbers in the code seem to represent some transformation based on the number of letters skipped or some similar pattern.

- For SQUARE:

- S -> R,

- Q -> P,

- A -> 51,

- U -> Q,

- R -> 2,

- E remains as it appears. The pattern is not entirely clear without more context.

- For CUBE:

- C -> B,

- U -> 5,

- B -> A,

- E -> 2.

- For TRIANGLE:

- Applying similar transformations, we derive:

- T -> S,

- R stays (or alter using unknown pattern),

- I seems like it could be related to 11,

- A stays (or becomes numerical),

- N remains similar,

- G becomes related to some patterns (M),

- L becomes similar or related to numeric.

- E -> 2.

- The correct coding pattern for TRIANGLE would appear in available options.

Option 4: SQ13FMK2 seems consistent with observed patterns.