WhichXSLifstatementchecksfortheexistenceofahomepageattributewithinanSTSUniversalUserXMLstructure?()

WhichXSLifstatementchecksfortheexistenceofahomepageattributewithinanSTSUniversalUserXMLstructure？（）

A、<xsl:iftest="//stsuuser:AttributeList/stsuuser:Attribute[attr=‘homepage‘]">

B、<xsl:iftest="//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‘])>