To understand the translation from the point \((4, -1)\) to \((6, -1)\), let's analyze the change in the x-coordinate.
The original point has an x-coordinate of 4, and after translation, the x-coordinate becomes 6. The change in the x-coordinate can be calculated as follows:
\[ 6 - 4 = 2 \]
Since the y-coordinate remains the same throughout this translation (\(-1\) remains \(-1\)), the translation modifies only the x-coordinate by adding 2.
This means that the function representing this translation can be written as:
\[ f(x) = x + 2 \]
Given the options, the correct answer is: B. \(f(x) = x + 2\).