$4 \cos \frac{7 \theta}{2} \cos \frac{3 \theta}{2} \sin 5 \theta=$

• A

  $\sin 10 \theta+\sin 7 \theta-\sin 3 \theta$
• B

  $\sin 10 \theta+\sin 7 \theta-\sin 5 \theta$
• Correct answer
  C

  $\sin 10 \theta+\sin 7 \theta+\sin 3 \theta$
• D

  $\sin 10 \theta+\sin 7 \theta+\sin 5 \theta$

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