(a)
Given differential equation can be rewritten as
$\left\lbrack 1 + \left( \frac{dy}{dx} \right)^{2} \right\rbrack^{\frac{3}{4} \times 12} = \left( \frac{d^{2}y}{dx^{2}} \right)^{\frac{1}{3} \times 12}$
$\Rightarrow$ $\left\lbrack 1 + \left( \frac{dy}{dx} \right)^{2} \right\rbrack^{9} = \left( \frac{d^{2}y}{dx^{2}} \right)^{4}$
Here, we see that order of highest derivative is 2 and degree is 4.