Bad Qubits — Learn Quantum by Doing

Multiple choice

In the class QMA (Quantum Merlin-Arthur), how does the witness (proof) differ from the witness in the classical class NP?

In QMA the witness is checked deterministically with zero error, unlike in NP
In QMA the witness may be a quantum state on poly(|x|) qubits, checked by a polynomial-time quantum verifier; in NP the witness is a classical bit string
QMA has no witness at all; only Arthur's coin flips matter
In QMA the witness must be a single classical bit, while in NP it can be any classical string