50. 下列 Visual Basic 程式片段執行後，變數 c 之值為何？ Dim s As String="Apocalypse" Dim t As String="aeiou" Dim d As String Dim c ,i,j As Integer For i=1To Len (s) d=Mid (s,i,1 ) j=1 While j<=Len (t) If Mid (t,j, 1)=d Then c=c+1 Exit While End If j=j+1 End While Next i 
(A) 1
(B) 2
(C) 3
(D) 4