如果数组a(下标1到n)满足a(1)≤a(2)≤…≤a(i-1)≤a(i)≥a(i+1)≥…≥a(n),则称数组a是单峰的,并称a(i)是数组a的“峰顶”。下列程序段用于查找数组a中的“峰顶”,并返回该“峰顶”值。

Dim a(1 To 10) As Integer

Function Search(L As Integer, R As Integer) As Integer

 M = (L + R) \ 2

 If a(M) < a(M - 1) And a(M) > a(M + 1) Then

    ⑴  

 ElseIf a(M) > a(M - 1) And a(M) > a(M + 1) Then

    ⑵  

 ElseIf a(M) > a(M - 1) And a(M) < a(M + 1) Then

   ⑶  

 End If

End Function

Private Sub Command1_Click()

 Label1.Caption = "“峰顶”值是:" + Str(Search(1, 10))

End Sub

上述程序中划线处可选语句为:

①Search = Search(M + 1 , R)

②Search = Search(L , M - 1)

③Search = a(M)

则(1)(2)(3)处的语句依次是（  ）

A、①②③

B、①③②

C、③①②

D、②③①