Which of the following series is divergent?

MATHEMATICS · Single correct · AP · Calculus BC · Infinite Sequences and Series · Infinite Sequences and Series

Problem

Which of the following series is divergent? (a)

\displaystyle \sum_{n=2}^{\infty} \frac{(-1)^{n}}{n\ln n}

(b)

\displaystyle \sum_{n=1}^{\infty} \frac{1}{\sqrt n}

(c)

\displaystyle \sum_{n=1}^{\infty} \frac{2^{n}}{n!}

(d)

\displaystyle \sum_{n=1}^{\infty} \frac{(-1)^{n}}{\sqrt n}