Convert the radical expression to its rational exponent form and simplify. Assume all variables are positive numbers. What is the rational exponent form of \(\sqrt[15]{x^{12}}\)? \nA) \(x^{\frac{12}{15}}\) \nB) \(x^{\frac{4}{5}}\) \nC) \(x^{\frac{3}{5}}\) \nD) \(x^{\frac{2}{5}}\)