A. $\lim _{x \rightarrow 0} \frac{\sin x^{2}}{x}=1$     B. $\lim _{x \rightarrow 0} \frac{\sin x}{x^{2}}=1$     C. $\lim _{x \rightarrow 0} \frac{\tan x}{x}=1$     D. $\lim _{x \rightarrow \infty} \frac{\sin x}{x}=1$