which statement is true for all functions f(x)

1. the graph of f(x) + k is the graph of f(x) shifted left or right by | k | units

2. the graph of -f(x) is the graph of f(x) reflected over the x-axis

3. the graph of -f(x) is the graph of f(x) reflected over the y-axis

4. the graph of f(kx) is the graph of f(x) shifted left or right by | k | units