2. For any real numbers $m$, $n$, $p$, it is required:
(1) to write the corresponding quadratic equation;
(2) to make the equation have $n^{2}-4 m p$ as the discriminant.

Among the following answers:
$$
\begin{array}{l}
m x^{2}+n x+p=0, \\
p x^{2}+n x+m=0, \\
x^{2}+n x+m p=0, \\
\frac{1}{a} x^{2}+n x+a m p=0(a \neq 0),
\end{array}
$$

The equation(s) that fully meet the requirements ( ).
(A) exactly 1
(B) exactly 2
(C) exactly 3
(D) all 4