$A B C D$ is a quadrilateral. Forces $\overrightarrow{A B}, \overrightarrow{C B}, \overrightarrow{C D}$ and $\overrightarrow{D A}$ act along its sides. What is their resultant?

• A

  $2 \overrightarrow{C D}$
• B

  $2 \overrightarrow{D A}$
• C

  $2 \overrightarrow{B C}$
• Correct answer
  D

  $2 \overrightarrow{C B}$

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