Simplify the complex fraction. \[ \frac{\frac{12}{x+h}-\frac{12}{x}}{h} \] Select one: a. $\frac{1}{x+h}$ b. $-\frac{12}{x(x+h)}$ C. $-\frac{1}{x+h}$ d. $\frac{12}{x(x+h)}$

Step 1 ：The given expression is a complex fraction. To simplify it, we can first combine the two fractions in the numerator into one by finding a common denominator. The common denominator of \(\frac{12}{x+h}\) and \(\frac{12}{x}\) is \(x(x+h)\).

Step 2 ：After combining the fractions in the numerator, we can then simplify the resulting fraction by dividing the numerator and the denominator by \(h\).

Step 3 ：The simplified form of the given complex fraction is \(-\frac{12}{x(x+h)}\).

Step 4 ：Final Answer: \(\boxed{-\frac{12}{x(x+h)}}\)