(c)
Put $x^{e} + e^{x} = t\ \ \ \Rightarrow \ e\left( x^{e - 1} + e^{x - 1} \right)dx = dt$
$\therefore\int_{}^{}\frac{x^{e - 1} + e^{x - 1}}{x^{e} + e^{x}}dx = \frac{1}{e}\int_{}^{}\frac{dt}{t} = \frac{1}{e}\log t + c = \frac{1}{e}\log{(x^{e} + e^{x})} + c$