Let α, β, γ, δ be real numbers such that α2 + β2 + γ2 ≠ 0 and α + γ = 1. Suppose the point (3,2,−1) is the mirror image of the point (1,0,−1) with respect to the plane αx + βy + γz = δ. Then which of the following statements is/are TRUE?
(A) α + β = 2
(B) δ - γ = 3
(C) δ + β = 4
(D) α + β + γ = δ