Question

Let v1 = -4

Answer 1

We're told (and we can confirm) that $v_3=2v_1-3v_2$, so $v_3$ is a linear combination of the other two vectors.

This means H is sufficiently spanned by $\{v_1,v_2\}$; no need for the third vector.

But this also means we can write either $v_1$ as a linear combination of $\{v_2,v_3\}$, and $v_2$ as a lin. com. of $\{v_1,v_3\}$. So any set of these three vectors taken two at a time will span the subspace H. Hence all of b, c, and d are acceptable.