There are n urns each containing (n+1) balls such that the i^th urn contains “i” white balls and (n+1−i) red balls. Let u_i be the event of selecting the i^th urn, i = 1, 2, 3 ..., n, and w denote the event of getting a white ball. If n is even and E denotes the event of choosing an even numbered urn {P (u_i) =  }, then the value of  is equal to

a)

b)

c)

d)