$\mathrm{A}, \mathrm{B}, \mathrm{C}, \mathrm{D}$ are any four points. If E and F are mid points of AC and BD respectively, then $\overline{\mathrm{AB}}+\overline{\mathrm{CB}}+\overline{\mathrm{CD}}+\overline{\mathrm{AD}}=$

• A

  $\overline{\mathrm{EF}}$
• B

  $2 \overline{\mathrm{EF}}$
• C

  $3 \overline{\mathrm{EF}}$
• Correct answer
  D

  $4 \overline{\mathrm{EF}}$

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