The graphs of two functions are shown here:

$\bullet y=a^x$ is shown with a solid line, where $a$ is a positive real number $\bullet y=f(x)$ is shown with a dashed line

[IMAGE_PLACEHOLDER]

Which of the following statements (1, 2, 3, 4) could be true?

1 $f(x)=b^x$ for some $b>a$

2 $f(x)=b^x$ for some $b<a$

3 $f(x)=a^{kx}$ for some $k>1$

4 $f(x)=a^{kx}$ for some $k<1$