The Following Questions Relate to the Three Figures Above, Which

The following questions relate to the three figures above, which indicate how the tubules in the kidney respond to the administration of the hormone vasopressin (AVP) .
-The density of the aquaporins in the presence of vasopressin was approximately

A) half as much as before the administration of vasopressin.
B) twice as much as before the administration of vasopressin.
C) four times as much as before the administration of vasopressin.
D) unchanged by the administration of vasopressin.