HTML optgroup Tag - javatpoint
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optgroup> - OPTGROUP TAG IN HTML
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HTML <optgroup> Tag - GeeksforGeeks
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File:HTML-select-optgroup-example-gl.png - Wikimedia Commons
OPTGROUP Tag in HTML || HTML Optgroup Tag
HTML <optgroup> Tag
html tutorial - <optgroup> Tag in HTML - html5 - html code - html form - In 30Sec by Microsoft Award MVP - | wikitechy
How to specify a label for an optgroup tag in HTML5 ? - GeeksforGeeks
