In a trapezoid, what does the height refer to?

In the context of a trapezoid, the height specifically refers to the perpendicular distance between the two bases. A trapezoid is defined as a quadrilateral that has at least one pair of parallel sides, known as bases. The height is essential in calculating the area of the trapezoid and is determined by dropping perpendicular lines from the vertices of one base down to the line that extends along the other base.

The other options do not accurately define the height of a trapezoid. The length of the longer base represents one of the sides of the trapezoid, but does not describe the measurement of height. Similarly, the sum of both base lengths is a different aspect related to the trapezoid's properties, and the longest side pertains to the trapezoid's sides rather than the height itself. Thus, the height is uniquely defined as the distance measured perpendicularly between the bases, making the first choice the correct one.