Evaluate ∬Dx dA\iint_D x \, dA∬DxdA where DDD is the triangle with vertices (0,0),(1,0),(0,1)(0,0), (1,0), (0,1)(0,0),(1,0),(0,1).
16\frac{1}{6}61
13\frac{1}{3}31
12\frac{1}{2}21
111