【VB单选题】下列关于 For ... Next 结构的格式中,正确的格式是( )

<p>A.For x=1 To Step 10 ... Next x&nbsp;</p><p>B.For x=3 To -3 Step -3 ... Next x&nbsp;</p><p>C.For x=1 To 2 : For y=1 To 5 ... Next x : Next y&nbsp;</p><p>D.For x=3 To 10 Step 3 ... Next y</p><p><br></p>