Correct answer is (C)

$\overrightarrow{A}\times \overrightarrow{B}=\overrightarrow{B}\times \overrightarrow{A}$

$\overrightarrow{A}\times \overrightarrow{B}-\overrightarrow{B}\times \overrightarrow{A}=0$

$\Rightarrow \overrightarrow{A}\times \overrightarrow{B}+\overrightarrow{A}\times \overrightarrow{B}=0$

$\therefore$ $\overrightarrow{A}\times \overrightarrow{B}=0$

$\Rightarrow AB\sin \theta =0$

$\theta =$ $0,\pi ,$$2\pi$ ........

from the given options, $\theta =\pi$