18. Let the wave function of two electrons at t = 0 be Ψ(x₁,s₁;x₂,s₂), where x₁ and x₂ are the positions, and s₁ and s₂ are the spins of the electrons. Given that the wave function can be factorized into spatial and spin parts, namely, Ψ(x₁,s₁;x₂,s₂) = ψ_a(x₁,x₂)χ_a(s₁,s₂) + ψ_b(x₁,x₂)χ_b(s₁,s₂), where χ_a(s₂,s₁) = -χ_a(s₁,s₂) and χ_b(s₂,s₁) = χ_b(s₁,s₂), which of the following statements is incorrect?
(A) ψ_a(x₁,x₂) = -ψ_a(x₂,x₁)
(B) ψ_b(x,x) = 0
(C) Ψ(x₂,s₂;x₁,s₁) = -Ψ(x₁,s₁;x₂,s₂)
(D) ψ_a(x₂,x₁)ψ_b(x₂,x₁) = -ψ_a(x₁,x₂)ψ_b(x₁,x₂)
(E) All the above are correct