Arectangle with points (0,0), (3,0), (3, 7), and (0,7) is rotated around the y-axis. which of the following is the vertical cross section of the three-dimensional figure formed? rectangle circle triangle cylinder

We have that
A rectangle with points (0,0), (3,0), (3, 7), and (0,7)

using a graph tool
see the attached figure
 
if the rectangle is rotated around the y-axis
then 
the three-dimensional figure formed is a cylinder with radius 3 units and height  7 units

and
the vertical cross-section  is a rectangle with 6 units x 7 units

the answer is 
rectangle