Explanation:

Using the first condition – There is one person between C and F, i.e. C _ F or F _ C. So, there are only two conditions.

Using the second condition – E is neither adjacent to A nor D, i.e. C E F or F E C.

Using the third condition F is opposite A and D is opposite to C, the six persons can occupy the positions only as given in the diagram below.

It is clear from the diagram, that B is opposite to E.

Hence, option 2 is the correct answer.