$\displaystyle \lim _ {x \rightarrow 0} \left (\csc ^ {2} x- \frac{1} {x^ {2}} \right)$ 의 값은?

• ①$0$
• ②$\displaystyle \frac{1} {6}$
• ③$\displaystyle \frac{1} {4}$
• ④$\displaystyle \frac{1} {3}$