$\;\lim \limits_{x \to 0}\Large\frac{a^{x}-b^{x}}{c^{x}-d^{x}}$ is

Question

\[\begin{array}{1 1}(1)\infty&(2)0\\(3)\log\frac{ab}{cd}&(4)\frac{\log(a/b)}{\log(c/d)}\end{array}\]