Concept:The degree of a differential equation is the power of the highest-order derivative after removing radicals and fractional exponents.Explanation:Start with the given equation:[1+(dxdy)2]43=(dx2d2y)31To eliminate the fractional powers, raise both sides to the least common multiple of the denominators 4 and 3, which is 12:[[1+(y′)2]43]12=[(y′′)31]12This simplifies to:[1+(y′)2]9=(y′′)4Now the equation is a polynomial in derivatives. The highest-order derivative is y′′ (second order), and its power is 4.Therefore, the degree of the differential equation is 4.Answer:4 (Option A)