The correct answer should be C)..Let us see how ..
It is given that Chandni is married and Tara is not married..Further a married person looks at unmarried is also given..
Now given Chandni looks at Sooraj ==> Sooraj is unmarried is followed from this instance
Also Sooraj looks at Taara ..Now Taara is not married .Also it is given : A married person looks at unmarried . So Sooraj has to be married as follows from this instance..
So both of the above instances are contradictory..
Hence it is an impossible event..But it is so if we are given information about who the unmarried person can look to..
Thus the given piece of information is insufficient.
Hence D) should be the correct answer..