A

$\displaystyle\sum\limits_{n=1}^{\infty}\dfrac{(-1)^{n+1}}{n\sqrt n}$

B

$\displaystyle\sum\limits_{n=1}^{\infty}\dfrac{(-1)^n}{n+1}$

C

$\displaystyle\sum\limits_{n=1}^{\infty}\dfrac{(-1)^{n-1}}{\sqrt{n+1}}$

D

$\displaystyle\sum\limits_{n=1}^{\infty}(-1)^{n+1}\dfrac{n}{(n+1)(n+3)}$