Solution
= Solution
{c}
The <binomial theorem> gives $\binom{2n}{n}\leq\sum_{k=0}^{2n}\binom{2n}{k}=4^n$. Therefore
$$
\left|\binom{2n}{n}3^{-2n}\sin n\right|\leq(4/9)^n.
$$
The <geometric series> with ratio $4/9$ converges. By the <comparison test>, the given <series> is \b[absolutely convergent].