If $A = \begin{bmatrix} a & b \\ c & d \end{bmatrix}$ (where $bc \neq 0$) satisfies the equation $x^2 + k = 0$,then:

  • A
    $a + d = 0$
  • B
    $k = -|A|$
  • C
    $k = |A|$
  • D
    both $(A)$ and $(C)$

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