If $\lim _{x \rightarrow 0}\left(\frac{\cos 4 x+a \cos 2 x+b}{x^4}\right)$ is finite, then the values of $a, b$ are respectively :

• A

  $5,-4$
• B

  $-5,-4$
• Correct answer
  C

  $-4,3$
• D

  4,5

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