Answer: D. 5
Explanation:
In the given figure , we have give a trapezioid ABCD with parallel sides BC= 3.3 units and AD= 6.7 units.
Also, E and F appears as the mid points of non parallel sides AB and CD and parallel to the bases BC and AD.
⇒ EF would be the median of trapezioid ABCD.
Also, we know that , the length of the median of a trapezoid equals to one-half the sum of the lengths of the two bases.
i.e. length of EF =

i.e. length of EF =

i.e. length of EF =

i.e. length of EF = 5 units.