Ummm, first things first...

$value = (sort values %category);
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will store the last value of the sorted list of values in $value, this is most likely not what you want. You are looking to print the value of %category that the key matches $form{'USER_INPUT'}? then use..

print $category{$form{'USER_INPUT'} if $category{$form{'USER_INPUT'};
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do you just want the value of Anim if the user inputs Anim, or do you want Build AND CAD when the user inputs 'd'?
                - Ant