Calling sub with 2-D array

If I have Dim a(15) as string Call WritetoSmith(a) Protected Sub WriteToExcelOrthers(ByVal ParamArray b() As String)
all is well. No problem.
But then I wanted to have a 2-D array
Dim c(15,29) as string Call WritetoSmith(c) Protected Sub WriteToExcelOrthers(ByVal ParamArray b() As String)

It would not accept this. The intellisense says "2-dimensional array of type string cannot be converted to string"

How can I send a 2-D array to the sub, please ?

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