Assuming this is associated with graphs then think of the graph:
You have your x and y axes, the x axis is horizontal going from left to right, the y axis goes vertical going up and down. Now... f(x) represents the x axis, meaning it would only be going left or right. Now, it adds 12 to that, the "+ 12". Now we all know that going right is positive, left is negative, so... the answer would be:
A. Right
I hope that helps, have a great rest of your day! ^ ^
{-Ghostgate-}
