1. Given the function $f(x)=a \ln x+x^{2}$ has an extremum at $x=1$. Then the value of the real number $a$ is ( ).
(A) -2
(B) -1
(C) 1
(D) 2
- 1. A.

It is known that $f^{\prime}(x)=\frac{a}{x}+2 x$.
Given that $f^{\prime}(1)=0$, solving yields $a=-2$.