A: Solution: "? X0 ∈ [2,4] and x0∈[2-a ≤ 0 "are true propositions,

So: "? X0 ∈ [2,4] and x0∈[2 ≤ a "are true propositions,

So 4≤a,

So "? X0 ∈ [2,4], x0∈[2-A ≤ 0 "is true and only if a≥4,

Because the range of a≥4 sufficient and unnecessary condition should be smaller than its range,

So it should be a≥5.

So choose one