If $u=\sin^{-1}\begin{pmatrix}\large\frac{x^{4}+y^{4}}{x^{2}+y^{2}}\end{pmatrix}$ and $f=\sin u$ then $f$ is a homogeneous function of degree

Question

$$\begin{array}{1 1}(1)0&(2)1\\(3)2&(4)4\end{array}$$