compute complete integral

Question

26. The complete integral of $(z-px-qy)^3=pq+2(p^2+q)^2$ is

1. $z=ax+by+\sqrt[3]{pq+2(p^2+q)^2}$
2. $z=ax+by+\sqrt[3]{ab+2(a^2+b)^2}$
3. $z=ax+by+\sqrt[3]{ab}+\sqrt[3]{2(a^2+b)^2}$
4. $z=ax+by+c$