In a quadrilateral $\mathrm{ABCD}$, which is not a trapezium, it is known that $\angle D A B=\angle A B C=60^{\circ}$. Moreover, $\angle C A B=\angle C B D$. Then.

• A

  $A B=B C+C D$
• B

  $A B=A D+C D$
• C

  $A B=B C+A D$
• Correct answer
  D

  $A B=A C+A D$

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