The degree of the differential equation $\left(\frac{d^2 y}{d x^2}\right)^2+\left(\frac{d y}{d x}\right)^2=x \sin \left(\frac{d^2 y}{d x}\right)$, is

1 2 3 none of these

none of these

Clearly, the given differential equation is not a polynomial in differential coefficients. So, its degree is not defined.