#### Answer

The right answer is (c).

#### Work Step by Step

We have
(a) $\lim_{n\to \infty} \frac{n^2}{n^2+1}=1$.
(b) $\lim_{n\to \infty} 2^n=\infty$.
(c) $\lim_{n\to \infty} (\frac{-1}{2})^{n}=0$.
Since $$\lim_{n\to \infty} (\frac{-1}{2})^{n}=0$$ then the right answer is (c).