Correct Answer: VIGOUR

Solution : Given:
GREGARIOUS

Now, let's compare all the option words with the word GREGARIOUS –
First option: VIGOUR; The letter V in the word VIGOUR is not present in the word GREGARIOUS.
Second option: ARIES; All the letters of ARIES are present in the word GREGARIOUS.
Third option: RASER; All the letters of RASER are present in the word GREGARIOUS.
Fourth option: SUGAR; All the letters of SUGAR are present in the word GREGARIOUS.

So, VIGOUR cannot be formed with the help of the letters of the word GREGARIOUS. Hence, the first option is correct.