Let $S_n$ denote the sum of the first $n$ terms of an arithmetic sequence $\{a_n\}$. If $S_3 = 6$, $S_5 = -5$, then $S_6 = $ ( ) A. $-20$ B. $-15$ C. $-10$ D. $-5$
Let $S_n$ denote the sum of the first $n$ terms of an arithmetic sequence $\{a_n\}$. If $S_3 = 6$, $S_5 = -5$, then $S_6 = $ ( )\\
A. $-20$\\
B. $-15$\\
C. $-10$\\
D. $-5$