Answer:
C, the 3rd one
Hope this helped! Have a great day!
Answer: top left
Reason: all plots have twenty dots. Count from either side. If the tenth and eleventh are both on six than that plot is correct. Top left is the only one like that. (the median of 20 being between 10 and 11)
You find a parallelogram area by this formula:

Where
b is its base and
h, its height.
You get
b's value applying distance between two points formula.
If A and B points form the base:

And
h is the perpendicular distance between both bases.
You can visit next link to know further about it:
https://www.ck12.org/geometry/Distance-Between-Parallel-Lines/lesson/Distance-Between-Parallel-Lines
-GEOM/
And in attached picture you can find an example in progress you may want to finish.