Answer:
D. plain quadrilateral
Explanation:
This is a vocabulary question.
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A parallelogram is a quadrilateral (4-sided plane figure) with both pairs of opposite sides parallel. A rhombus is a special case of a parallelogram in which the sides have equal lengths.
A trapezoid is quadrilateral with exactly one pair of parallel sides. An isosceles trapezoid is one that has equal-length non-parallel sides.
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The given figure has no parallel sides, so is none of the above. It is a ...
plain quadrilateral