Trong các mệnh đề sau mệnh đề nào sai ? \(\mathop {\lim }\limits_{x \to - \infty } \left( {\sqrt {{x^2} - x + 1} - x} \right) = - \frac{1}{2}\)

A. \(\mathop {\lim }\limits_{x \to  - \infty } \left( {\sqrt {{x^2} - x + 1}  - x} \right) =  - \frac{1}{2}\)

B. \(\mathop {\lim }\limits_{x \to  + \infty } \left( {\frac{{\sqrt {{x^2} - x + 1}  - 2}}{{2x + 3}}} \right) = \frac{1}{2}\)

C. \(\mathop {\lim }\limits_{x \to  - {1^ - }} \frac{{3x + 2}}{{x + 1}} =  + \infty \)

D. \(\mathop {\lim }\limits_{x \to  + \infty } \frac{{3x - 2}}{{2 - x}} =  - 3\)