Lumen OHM

What function is graphed below?

$\displaystyle {f{{\left({x}\right)}}}={3}^{{x}}$
$\displaystyle {f{{\left({x}\right)}}}={5}^{{x}}$
$\displaystyle {f{{\left({x}\right)}}}={4}^{{x}}$
$\displaystyle {f{{\left({x}\right)}}}={2}^{{x}}$
$\displaystyle {f{{\left({x}\right)}}}={\left(\frac{{1}}{{2}}\right)}^{{x}}$
$\displaystyle {f{{\left({x}\right)}}}={\left(\frac{{1}}{{5}}\right)}^{{x}}$
$\displaystyle {f{{\left({x}\right)}}}={\left(\frac{{1}}{{4}}\right)}^{{x}}$
$\displaystyle {f{{\left({x}\right)}}}={\left(\frac{{1}}{{3}}\right)}^{{x}}$