Answer is (b). 449.02 sqr ft.
Total area including tree and leaves will be:
π r^2 = 3.14 * (12)^2 = 3.14*144 = 452.16 sqr ft
Area of tree:
π r^2 = 3.14 * (1)^2 = 3.14*1 = 3.14 sqr ft.
So, the area covered by leaves will be:
452.16-3.14 = 449.02 sqr ft