Explain the question

5. $\mathrm{If} \overrightarrow{\mathrm{A} }\times \overrightarrow{\mathrm{B} }= \sqrt{3} \overrightarrow{\mathrm{A}}.\overrightarrow{\mathrm{B} }\mathrm{then} \left|\overrightarrow{\mathrm{A}}+\overrightarrow{\mathrm{B}}\right| \mathrm{will} \mathrm{be}$
(1) A + B
(2) ${\left({\mathrm{A}}^2+{\mathrm{B}}^2+\sqrt{3}\mathrm{AB}\right)}^{\frac{1}{2}}$)
(3) ${\left({\mathrm{A}}^2+{\mathrm{B}}^2-\sqrt{3}\mathrm{AB}\right)}^{\frac{1}{2}}$
(4) ${\left({\mathrm{A}}^2+{\mathrm{B}}^2+\mathrm{AB}\right)}^{\frac{1}{2}}$ ^​​​​