Quiz: Hall's Marriage Theorem

You have $4$ left nodes with neighbor sets $\{1,2\}$, $\{1,2\}$, $\{1,2\}$, $\{3\}$. Does a perfect matching exist?

1. A.Yes, because every left node has at least one neighbor
2. B.Yes, Hall's condition holds for all subsets
3. C.No, because node $4$ has only $1$ neighbor
4. D.No, the first $3$ nodes share only $2$ neighbors, violating Hall's condition