Correct option(d) 2.13!/14!
Explanation:
15 persons can be seated round a table in 14! ways. If 4 persons are to be included between A and B, they can be arranged in 13C4 x 4! ways, now total number of arrangements is 13C4 x 4! × 9! × 2! = 2.13!
Hence the probaility is 2.13!/14! = 2/14 = 1/7