In a certain code language, (A) ‘pit dar na’ means ‘you are good’ (B) ‘dar tok pa’ means ‘good and bad’ (C) ‘tim na tok’ means 'they are bad’ In that language, which word stands for 'they' ?

Justification:      

In the first and third statements, the common word is 'na' and the common word is 'are'.

So, 'na' means 'are'.
In the second and third statements, the common code word is 'tok' and the common word is 'bad'.
So, 'tok' means 'bad'.
Thus, in the third statements, 'tim' stands for 'they'.