(a) Carefully determine the convergence of the series $\sum\limits_{n=1}^{\infty} {(-1)^n\over 3 n}$. The series is
A. absolutely convergent
B. conditionally convergent
C. divergent

(b) Carefully determine the convergence of the series $\sum\limits_{n=1}^{\infty} {(-1)^n\over 3^n}$. The series is
A. absolutely convergent
B. conditionally convergent
C. divergent