Correct Answer: DISMISS

Solution : Given:
ADMISSION

Now, let's compare all the option words with the word ADMISSION –
First option: MISSION; All the letters of MISSION are present in the word ADMISSION .
Second option: DISMISS; In the word DISMISS, three S are present whereas in the word ADMISSION two S are present. Therefore, all the letters of DISMISS are not present in the word ADMISSION.
Third option: MASONS; All the letters of MASONS are present in the word ADMISSION .
Fourth option: NOMADS; All the letters of NOMADS are present in the word ADMISSION .

So, from the above, only DISMISS cannot be formed using the letters of the word ADMISSION. Hence, the second option is correct.