For $k \geq 1$, the value of $\binom { n } { 0 } + \binom { n + 1 } { 1 } + \binom { n + 2 } { 2 } + \cdots + \binom { n + k } { k }$ equals\\
(a) $\binom { n + k + 1 } { n + k }$.\\
(B) $( n + k + 1 ) \binom { n + k } { n + 1 }$.\\
(C) $\binom { n + k + 1 } { n + 1 }$.\\
(D) $\binom { n + k + 1 } { n }$.