To determine the function that represents the translation from the point \((4, -1)\) to the point \((6, -1)\), we need to focus on the x-coordinate.
The x-coordinate changes from \(4\) to \(6\), which is an increase of \(2\). Therefore, the translation can be described by the function that adds \(2\) to the input \(x\):
\[ f(x) = x + 2 \]
So the correct answer is:
O f(x) = x + 2.