Explanation:

- The word 'LABOUR' is encoded as '279'. Each letter might be assigned a specific numerical value.

- Similarly, 'EXHALE' becomes '321'. The same principle applies here.

- To encode 'CAUTIOUS', we need to look for a consistent pattern or rule applied to the words 'LABOUR' and 'EXHALE'.

- Analyzing the options:

- Option 1: 535

- Option 2: 525

- Option 3: 553

- Option 4: 552

- Without an explicit letter-to-number mapping, reasoning from LABOUR and EXHALE leads us to the correct pattern.

- For the code language, Option 3: 553 is the most appropriate choice for encoding 'CAUTIOUS'.

Correct Answer: 553