Solve this following

Mark $(\sqrt{)}$ against the correct answer in the following:

If $x^{p} y^{q}=(x+y)^{(p+q)}$ then $\frac{d y}{d x}=?$

A. $\frac{\mathrm{x}}{\mathrm{y}}$

B. $\frac{y}{x}$

C. $\frac{x^{p-1}}{y^{q-1}}$

D. none of these