XML::DOM::Lite is weird. As you can see from the code below you can get the attribute of each found node normally, but to get the text value you have to call childNodes() on the node first and then call nodeValue(). Heavy use of Data::Dumper was required to work this one out.

my $B = $doc->selectNodes("A/B");

if (defined($B) ) {
    for my $node (@$B) {
        my $cnodes = $node->childNodes;
        for my $cnode (@$cnodes) {
            my $val = $cnode->nodeValue;
            print qq|Value of B is: $val\n|;
        }
    }
}

my $D = $doc->selectNodes("A/C/D");

if (defined($D) ) {
    for my $node (@$D) {
        my $attr = $node->getAttribute("d_attribute");
        print qq|Attribute 'd_attribute' of D is: $attr\n|;
        my $cnodes = $node->childNodes;
        for my $cnode (@$cnodes) {
            my $val = $cnode->nodeValue;
            print qq|Value of D is: $val\n|;
        }
    }
}
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On your sample XML, after I fixed the attribute (d_attribute="d_attribute_value") this produces:

Value of B is: B value
Value of B is: B value
Attribute 'd_attribute' of D is: d_attribute_value
Value of D is: D_Value
Attribute 'd_attribute' of D is: d_attribute_value
Value of D is: D_Value
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