A quadrilateral with one pair of parallel side is a
A) Parallelogram
B) Square
C) Rectangle
D) Trapezium

Hint: In order to solve this question, we must know that quadrilaterals have special properties. Also we have to make figures, this will give us a clear picture of what our approach should be. By understanding the properties of different quadrilaterals will help us in solving this question.

Complete step-by-step answer:
Quadrilaterals are a special type of polygon. The meaning of the word “quadrilateral” is “quad” means “four” and “lateral” is derived from the Latin word for “side”. So a quadrilateral is a four-sided polygon.
Let’s start explaining all the options one by one,

(A) Parallelogram –

The quadrilateral with two pairs of parallel sides is called parallelogram. A parallelogram has opposite sides parallel and equal in length. Also opposite angles are equal.
As, parallelogram has two pairs of parallel sides. So, option A is incorrect.

(B) Square-

A square is one of the most basic geometric shapes. It is a special case of parallelogram that has four congruent sides and four right angles that is ${90^ \circ }$.
As, square has four congruent sides. So option B is incorrect.

  (C) Rectangle-

A rectangle is a parallelogram because its pairs of opposite sides are parallel. A rectangle also has the special characteristic that all of its angles are right angles; all four of its angles are congruent.
As, rectangle has 2 pairs of parallel sides. So, the option C is incorrect.

(D) Trapezium-

A trapezium is a quadrilateral with exactly one pair of parallel sides. One pair of opposite sides being parallel and the other pair not parallel.
As, trapezium has exactly one pair of parallel sides. So, the right answer is option D.

Note: Whenever we face such types of questions, the key concept is that we have to examine all the quadrilaterals one by one given in this question. By examining one by one diagrammatically and theoretically we find out that trapezium is a quadrilateral with one parallel side, By using this approach we will get our answer.