From the clues, "A is immediate left of B" and "A is immediate right of C" together give the order C, A, B. "C is immediate right of F" places F right before this group, giving F, C, A, B. "D is immediate right of E, and E is to the left of F" places E and D before F, giving the complete order E, D, F, C, A, B.
In a row of six seats, the centre positions are the 3rd and 4th, which here are occupied by F and C.
So option 3, "F & C", is correct.