A siren produces a sound whose amplitude goes as $x=10 \cos (3 \omega t) \cos (2 \omega t)+5 \cos (5 \omega t)$. Tuning forks with natural frequency $f$ will resonate with the siren for the value(s) of $f$ given by

• Correct answer
  A

  $f=\frac{5 \omega}{2 \pi}$
• Correct answer
  B

  $f=\frac{\omega}{2 \pi}$
• C

  $f=\frac{3 \omega}{2 \pi}$
• D

  $f=\frac{\omega}{\pi}$

Hence, the correct answer is options: 'A', 'B'.