Modifying A VBA Code To Del Rows

I am trying to modify the below code in order for it to:

1) Check the cells in Column A to find any blank cells and zero values. If the macro finds a blank cell or a zero then delete the entire row.
2) Check the cells in Column D for any blank cells and "N/A" (this N/A is text, it is not an excel error). If the macro finds a blank cell or "N/A" then delete the entire row.

Here is the old code


Sub DL()
Dim lastrow As Long, i As Long
With ActiveSheet
On Error Resume Next
.Columns(3).SpecialCells(xlCellTypeFormulas, xlErrors).EntireRow.Delete
On Error GoTo 0
lastrow = .Cells(Rows.Count, 3).End(xlUp).Row
For i = lastrow To 1 Step -1
If .Range("C" & i).Value = 0 And .Range("D" & i).Value = 0 Then .Rows(i).Delete
If .Range("C" & i).Value = "N/A" Then .Rows(i).Delete
Next i
End With
End Sub
Here is the modified code...


Sub DL()
Dim lastrow As Long, i As Long
With ActiveSheet
On Error Resume Next
.Columns(3).SpecialCells(xlCellTypeFormulas, xlErrors).EntireRow.Delete
On Error GoTo 0
lastrow = .Cells(Rows.Count, 3).End(xlUp).Row
For i = lastrow To 1 Step -1
If .Range("A" & i).Value = 0 And .Range("A" & i).Value = "" Then .Rows(i).Delete
If .Range("D" & i).Value = "" and .Rang("D" & i).Value ="N/A" Then .Rows(i).Delete
Next i
End With
End Sub

1) Is this the correct and efficient way to accomplish the task?

2) How to i change this in order to select a specific sheet?