Based on the information provided, the common feature of the polygons A, B, C, and D is that "Each appears to have exactly one pair of parallel sides."
Since you mentioned they all have one pair of parallel sides, this indicates that they are most likely trapezoids, as trapezoids are defined as quadrilaterals that have at least one pair of parallel sides. If this is the focus, the most specific answer would be:
"Each appears to be a trapezoid."
If you are looking for the most relevant or accurate statement regarding their characteristics as quadrilaterals and specifically as trapezoids with one pair of parallel sides, you could also consider:
"Each appears to have exactly one pair of parallel sides."
However, since trapezoids are a specific type of quadrilateral, saying "Each appears to be a trapezoid" might be the best choice if the goal is to classify them accurately based on their properties.