Correct Answer - B
The total number of ways of selecting 2 persons out of n persons sitting in a row is
.
n
C
2
.
.
Number of ways in which two adjacent persons are selected from n persons sitting in a row =(n-1)
Hence, required probability
=
.
n
C
2
−
(
n
−
1
)
.
n
C
2
=
1
−
2
n
=