If six persons sit in a row, then the probability that three particular persons are always together is ?
Options:
(A) 1/3
(B) 1/9
(C) 1/5
(D) 1/7
(E) 1/1 Think first, then make a decision. Some random thoughts:

Show your work and conclude with the exact phrasing "Therefore, the final answer is [answer]." where [answer] is just the final number or expression that solves the problem.
user
Six persons can be arranged in a row in 6! ways. Treat the three persons to sit together as one unit then there four persons and they can be arranged in 4! ways. Again three persons can be arranged among them selves in 3! ways. Favourable outcomes = 3!4! Required probability = 3!4!/6! = 1/5 So the answer is (C).