Which of the following is equal to (nr)+(nr−1)\binom{n}{r} + \binom{n}{r-1}(rn)+(r−1n)?
(nr+1)\binom{n}{r+1}(r+1n)
(n+1r)\binom{n+1}{r}(rn+1)
(n2r−1)\binom{n}{2r-1}(2r−1n)
n×(n−1r−1)n \times \binom{n-1}{r-1}n×(r−1n−1)