Answer:
D. 26.5 mm
Explanation:
A median of trapezoid is a line segment between the midpoints of the legs of a trapezoid (look at the picture).
The formula of a length of a median of a trapezoid:
![(a+b)/(2)](https://img.qammunity.org/2020/formulas/mathematics/middle-school/9lu7b6s8wcc1rjyee6o4zox5jhujv4i675.png)
a, b - bases
We have a = AB = 19mm, and b = DC = 34 mm. Substitute:
![(19+34)/(2)=(53)/(2)=26.5\ mm](https://img.qammunity.org/2020/formulas/mathematics/middle-school/e6aqldsfwgoq3zdt4nufwqr4vm98k86354.png)