Answer:
Option D. 4.5
Explanation:
In the given diagram FGAD is the trapezoid with the given sides FG = 3 units and AD = 6 units.
Now we have to calculate the Median IJ.
Since median of a trapezoid is represented by the formula =

Therefore, median IJ =

=
= 4.5
Therefore, Option D. 4.5 will be the answer.