To analyze the transformations from \( f(x) = x \) to \( f(3x) - 13 \):
- Start with \( f(x) = x \): This is the identity function.
- Transform to \( f(3x) \):
- Replacing \( x \) with \( 3x \) in \( f(x) \) results in a horizontal compression by a factor of 3. This means that the graph is compressed towards the y-axis.
- Then apply \( -13 \):
- Subtracting 13 from the function shifts the entire graph downward by 13 units.
Putting these transformations together, the final transformation from \( f(x) = x \) to \( f(3x) - 13 \) involves a horizontal compression and a downward shift.
Therefore, the correct response is:
compressed horizontally and shifted down.