The correct answer which is different from all the other options is  

4. LORD

This is because Lord itself is a meaningful word, meaning a noble person. Whereas all the other options namely  

1. CFIL

2. GIKN

3. FHKN do not have any meaning.

They are meaningless words or words whose letters are not arranged properly to form meaningful words.

FHKN is the correct answer, since it is the special case which has no vowel in it.

A vowel is a discourse sound made by the vocal folds. It is likewise a kind of letter in the letters in order.

The letters of the English letters in order are either vowels or consonants or both.

A vowel sound originates from the lungs, through the vocal lines, and isn't blocked, so there is no rubbing.