The number of real values of ' $a$ ', for which the system of equations $2 x+3 y+a z=0$, $x+a y-2 z=0$ and $3 x+y+3 z=0$ has nontrivial solutions is

• A

  2
• B

  1
• Correct answer
  C

  0
• D

  Infinity

Hence, the correct answer is option: 'C'.