Answer:
B. 18
Step-by-step explanation:
Quadrilateral ABCD is a rectangle.
Diagonals AC and BD intersect at point E.
Diagonals of a rectangle are equal in length.
[tex]\implies BD = AC[/tex]
Diagonals of a rectangle bisect each other.
[tex]\implies\frac{1}{2} BD = \frac{1}{2} AC\\\\\implies DE = \frac{1}{2} \times 36\\ \\ \implies DE = 18[/tex]
