Mathematical analysis $2$

Exercise $1.$ Let $=\{(x,y,z)in{R}^3|0x1,0yx,z=x^3+y^2\}$ and let $F$:$R^3{R}^3$ be the vector field given by $F(x,y,z)=(\frac{1}{3}x,\frac{1}{2}y,z-4x).$ The flux of $F$ through $$ in the direction vec$(n)$ pointing upward is equal to

A$)\frac{2}{3}$

B$)-\frac{4}{3}$

C$)0$

D$)-\frac{5}{3}$