Concerning the carotid sinus, the right description is
A、It is a dilatation at the posterior wall of the common carotid artery.
B、It is a dilatation at the point of the bifurcation of the common carotid artery.
C、It is a small ball struture behind the point of division of the common carotid artery.
D、It is a chemoreceptor.
E、All above are wrong.