51. a random walker travels along a one- dimensional discrete lattice (labelled by points-n, -n+1, ..,.0, .n-1, n) by putting random steps of length i unit towa

51. A random walker travels along a one- dimensional discrete lattice (labelled by points-N, -N+1, ..,.0, .N-1, N) by putting random steps of length I unit towards left or right. If the initial position is zero, the probability of finding the walker at the 0th position in a6 step walk is 9 (A)256 (B) 18 (C) (D) 16