Okay, here are the solutions in English. 2. Finding the inverse function of $f(x) = 1-2x$ Step 1: Write the function as $y = f(x)$. $$y = 1-2x$$ Step 2: Swap $x$ and $y$ to find the inverse relationship. $$x = 1-2y$$ Step 3: Solve for $y$. Subtract 1 from both sides: $$x - 1 = -2y$$ Divide by -2: $$\frac{x-1}{-2} = y$$ $$y = \frac{1-x}{2}$$ Step 4: Express the result as $f^{-1}(x)$. $$f^{-1}(x) = \frac{1-x}{2}$$ The correct option is A. $$\boxed{\text{A. } \frac{1-x}{2}}$$