$3 \lambda \vec{c}+2 \mu(\vec{a} \times \vec{b})=0$ then

• A

  $3 \lambda+2 \mu=0$
• Correct answer
  B

  $3 \lambda=2 \mu$
• C

  $\lambda=\mu$
• D

  $\lambda+\mu=0$

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