Step 1: Concept
A differential equation $M dx + N dy = 0$ is exact if $\frac{\partial M}{\partial y} = \frac{\partial N}{\partial x}$.
Step 2: Meaning
Rewrite the given equation: $(x + x^{8} + py^{2}) dx + (y^{8} - y + qxy) dy = 0$. Here $M = x + x^{8} + py^{2}$ and $N = y^{8} - y + qxy$.
Step 3: Analysis
Calculate partial derivatives: $\frac{\partial M}{\partial y} = 2py$ and $\frac{\partial N}{\partial x} = qy$.
Step 4: Conclusion
For the equation to be exact, we set $2py = qy$. Solving for the constants gives $2p = q$.
Final Answer: (A)