Which diagram shows electrons violating the Pauli exclusion principle?

The Pauli exclusion principle says that two electrons in the same orbital must have opposite spins, shown as one up arrow and one down arrow. In C, the second and third boxes each show two up arrows, so the electrons in each of those orbitals have identical spins. That violates the principle; the other diagrams do not show two same-spin electrons in one box.

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