Bad Qubits — Learn Quantum by Doing

Multiple choice

The Steane code is built from the classical [7,4] Hamming code by taking H_X = H_Z = H, giving three X-type and three Z-type stabilizer generators on 7 physical qubits. How many logical qubits k does it encode?

k = 1
k = 4
k = 3
k = 7