Identify the cross section shown.
a. rectangle
b. circle
c. trapezoid
d. pentagon

Option : a is the correct answer.
a. rectangle.
From the figure that is provided to us we see that the cross-section is in the shape of a quadrilateral such that it has two pair of parallel sides.
b)
circle
A circle does not have any edge or sides.
Hence, option: b is incorrect.
c)
Trapezoid
A trapezoid is a quadrilateral with one pair of parallel sides and one pair of unparallel sides.
Hence, option: c is incorrect.
d)
Pentagon
A pentagon is a polygon with 5 sides.
Hence, option: d is incorrect.
Hence, the best possible answer is:
Rectangle