Correct Answer: SITUATION

Solution : Given:
ADMINISTRATION

Now, let's compare all the option words with the word ADMINISTRATION –
First option: STRAIN; All the letters of STRAIN are present in the word ADMINISTRATION.
Second option: TRADITION; All the letters of TRADITION are present in the word ADMINISTRATION.
Third option: SITUATION; All the letters of SITUATION are not present in the word ADMINISTRATION. U is not present in the word ADMINISTRATION.
Fourth option: RATION; All the letters of RATION are present in the word ADMINISTRATION.

So, from the above, only SITUATION cannot be formed using the letters of the word ADMINISTRATION. Hence, the third option is correct.