Bad Qubits — Learn Quantum by Doing

Multiple choice

Per this lesson, what does it mean for a gate set to be universal for single-qubit operations?

Any 2x2 unitary can be approximated to arbitrary precision by a finite circuit of gates from the set
Every 2x2 unitary can be expressed exactly by a single gate from the set
The set can implement any operation using exactly one gate
The set contains all infinitely many 2x2 unitaries explicitly