You can draw vertical line, and get 2 rectangles.
1) First one with sides 2 and 7.
2) Second one with sides 1 and (5-2) = 3, 1 and 3.
3) Area of the first one =2*7=14 units²
4)Area of the second one = 1*3=3 units²
5) Area of the whole polygon = 14+3=17 units²
Answer C. 17units².
