Упрости выражение и выбери верный ответ

\(\dfrac{1}{x(x-3)}+\dfrac{1}{(x-3)(x-6)}+\dfrac{1}{(x-6)(x-9)}+\dfrac{1}{(x-9)(x-12)}=\) [ \(\frac{4}{x(x-12)}\) | \(x-12\) | \(\frac{4}{x-12}\) | \(\frac {1}{x(x-12)}\) ]