Select all pairs of parallel vectors.
\(\begin{bmatrix}-3\\-6\\3\end{bmatrix}\), \(\begin{bmatrix}5\\10\\-5\end{bmatrix}\) \(\begin{bmatrix}3\\-6\\3\end{bmatrix}\), \(\begin{bmatrix}-1\\2\\-1\end{bmatrix}\) \(\begin{bmatrix}1\\0\\1\end{bmatrix}\), \(\begin{bmatrix}-1\\0\\1\end{bmatrix}\) \(\begin{bmatrix}2\\0\\-1\end{bmatrix}\), \(\begin{bmatrix}-8\\0\\4\end{bmatrix}\)

Source

[Nicholson] W. Keith Nicholson, Linear Algebra with Applications, Lyryx 2021, Open Edition, Problem 4.1.7.