What A Series

Calculus Level 3

If $f(x)=(x+1)(x+2)(x+3) \ldots (x+n)$ then what is $f^{'}(0)$ ?

n!(1+\frac{1}{2}+\frac{1}{3}+.....\frac{1}{n})

(1+\frac{1}{2}+\frac{1}{3}+.....\frac{1}{n})

1

-1

n\times{n!}

0