Write the coefficient of $x^2$ in each of the following?
(1) $2+x^2+x$
(2) $2-x^2+x^3$
(3) $\frac{\pi }{2}{x}^2+x$
(4) $\sqrt{2}x-1$

The correct option is D: $1,-1,\frac{\pi }{2},0$

The constant multiplied to $x^2$ is the coefficient of $x^2$

(1) $2+x^2+x\to$ coefficient of $x^2=1$

(2) $2-x^2+x^3\to$ coefficient of $x^2=-1$

(3) $\frac{\pi }{2}{x}^2+x\to$ coefficient of $x^2=\frac{\pi }{2}$

(4) $\sqrt{2}x-1\to$ coefficient of $x^2=0$