已知有下面过程:Private Sub proc1(a As Integer,b As String,Optional x As Boolean) ......End

已知有下面过程： Private Sub proc1(a As Integer,b As String,Optional x As Boolean) ...... End Sub 正确调用此过程的语句是______。

A．Call procl(5)

B．Call procl 5,"abc",False

C．procl(12,"abc",True)

D．procl 5,"abc"