Hamster
Paragraph after invalid sole OPTION
Paragraph before invalid sole OPTGROUP
Paragraph after invalid OPTGROUP and valid mixed SELECT with and without OPTGROUP
Paragraph after valid mixed SELECT with and without OPTGROUP and before invalid mixed unclosed OPTION/OPTGROUP
Paragraph after invalid mixed unclosed OPTION/OPTGROUP. In web-browsers (Firefox and Chrome) this P and all consecutive content is invisibleMDN