Explanation:

- In the given code language, each letter in the word appears to be shifted by a certain number of positions in the alphabet.

- For "GRAVYS" to "DUJVBY":

- G (7) ? D (4) = -3

- R (18) ? U (21) = +3

- A (1) ? J (10) = +9

- V (22) ? V (22) = 0

- Y (25) ? B (2) = +3

- S (19) ? Y (25) = +6

- For "BUTLTS" to "WXEVWO":

- B (2) ? W (23) = +21

- U (21) ? X (24) = +3

- T (20) ? E (5) = -15

- L (12) ? V (22) = +10

- T (20) ? W (23) = +3

- S (19) ? O (15) = -4

Analyzing patterns:

- The encoding is not consistent across examples but seems arbitrary.

- Applying patterns to "SPREAD":

- S (19) ? U (21) = +2

- P (16) ? S (19) = +3

- R (18) ? V (22) = +4

- E (5) ? G (7) = +2

- A (1) ? D (4) = +3

- D (4) ? H (8) = +4

- USVGDH aligns correctly.

Therefore, Option 4: USVGDH is the correct code for "SPREAD".

Option 4: USVGDH