The correct option is A 38 cm
Area of trapezium
= 12×(a+b)×h,
where a and b are the lengths of the parallel sides and h stands for the perpendicular distance between the parallel sides.
⇒12×(84+b)×26=1586 cm2
⇒(84+b)×13=1586
⇒(84+b)=158613=122
⇒b=122−84
∴b=38 cm
So, the length of the other parallel side is 38 cm.