Determine if the pairs of vectors below are "parallel", "orthogonal", or "neither".
$\mathbf a = \langle -3, 1, -3 \rangle$ and $\mathbf b = \langle -15, 5, 50/3 \rangle$ are

$\mathbf a = \langle -3, 1, -3 \rangle$ and $\mathbf b = \langle -15, 5, -15 \rangle$ are

$\mathbf a = \langle -3, 1, -3 \rangle$ and $\mathbf b = \langle 12, -4, 13 \rangle$ are