Answer:21 units^2.
Explanation:
I do the box method. I took the pic, put it into MSPaint, and drew a box around the... b o x.
Then I took the area of the drawn box (7*7) and subtracted the area of the triangles you get.
The one on the top was a 7*3 and divided the result by 2 to get 10.5.
The bottom one is also a 7*3 and you still get 10.5.
Add em together to get 21.
TL;DR: A