Which XSL if statement checks for the existence of a homepage attribute within an STS Universal User XML structure?（）
- A<xsl:if test="//stsuuser:AttributeList/stsuuser:Attribute[attr='homepage']">
- B<xsl:if test="//stsuuser:AttributeList/stsuuser:Attribute[@name='homepage']">
- C<xsl:if-exists="//stsuuser:AttributeList/stsuuser:Attribute/custom:Homepage">
- D<xsl:if-exists="//stsuuser:AttributeList/stsuuser:Attribute[@name='homepage'])>