\(\(\(SetOptions[
      XML`MathML`ExpressionToMathML, \ "NamespacePrefixes" -> {"http://www.w3.org/1998/Math/MathML" -> "m"}, \ "Formats" -> {"ContentMathML"}]\)\(\ \)\(
\)
    \)\)

\(\(\(SetOptions[
      XML`MathML`BoxesToMathML, \ "NamespacePrefixes" -> {"http://www.w3.org/1998/Math/MathML" -> "m"}, \ "Formats" -> {"ContentMathML"}]\)\(\ \)\)\)

\(\(\(SetOptions[Export, \ 
      ConversionOptions -> {"NamespacePrefixes" -> {"http://www.w3.org/1998/Math/MathML" -> "m"}, \ "Formats" -> {"ContentMathML"}}]\)\(\ \)\)\)

\(\(\(\ \)\(SetOptions[ExportString, 
      ConversionOptions -> {"NamespacePrefixes" -> {"http://www.w3.org/1998/Math/MathML" -> "m"}, "Formats" -> {"ContentMathML"}}]\)\)\)