Multiple choice
Run this circuit, then measure all 4 qubits at once. What is the probability of the joint outcome |1111⟩ (qubit 0 leftmost)?
const c = circuit(4); c.h(0); c.cx(0, 1); c.cx(1, 2); c.cx(2, 3); return c;
Commit your prediction for P(|1111⟩) — then run it.