Explanation:

- In the given code language:

- ‘this is fact’ is coded as ‘cuz duz ruz’.

- ‘fact is fictional’ is coded as ‘guz ruz cuz’.

- ‘doubt is clear’ is coded as ‘cuz kuz buz’.

- By analyzing the codes:

- The word ‘is’ appears in all phrases and is consistently coded as ‘cuz’.

- The word ‘fact’ appears in the first two phrases. ‘fact’ must be coded as ‘ruz’.

- The word ‘fictional’ appears in the second phrase, coded as ‘guz’.

- The word ‘this’ appears in the first phrase, coded as ‘duz’.

- For ‘this is fictional’:

- ‘this’ is ‘duz’.

- ‘is’ is ‘cuz’.

- ‘fictional’ is ‘guz’.

- Therefore, ‘this is fictional’ should be coded as: duz guz cuz

Option 1: duz guz cuz