If a problem states "$y$ is directly proportional to $x$," what can you immediately infer about $y$ when $x=0$?

$y$ can be any constant because direct proportionality only applies to nonzero $x$-values unless specified otherwise

$y$ will equal $k$ because the constant of proportionality determines the value when $x=0$

$y$ must be undefined because direct proportionality makes $y$ dependent on the reciprocal of $x$ whenever $x$ is zero

$y$ must equal $0$ because $y=kx$ and $k$ is finite, so $y=0$