Which is a quadrilateral with only one pair of opposite sides parallel?
A quadrilateral is a closed polygon formed by four line segments.
Let's know more about trapezium.
The trapezium is the quadrilateral that has one pair of parallel sides. The figure of a trapezium is shown below.
add the vertices in figure: A, B, C and D
Here, AB || CD.
Hence, ABCD is a trapezium.