The function given is \( f(x) = 1x \), which simplifies to \( f(x) = x \).
This is a linear function that passes through the origin and increases without bound. Since it is a linear function, it does not have a horizontal asymptote; it continually increases as \( x \) increases, and it decreases without bound as \( x \) decreases.
However, if you meant to refer to \( f(x) = \frac{1}{x} \), which is a common function, it approaches the y-value of \( 0 \) as \( x \) approaches either \( \infty \) or \( -\infty \) (but never touches or crosses it).
Given the options provided, if the function is indeed \( \frac{1}{x} \):
The correct answer is: y = 0.