Instead of using an element of select-HTML content, perhaps consider using a div with n other divs inside it, each with their identifier as the identifier of the subtopic (probably you will need to add something if the identifiers are numeric). Show the div on click whatever, select a subtopic when you click on a single subtype of a div. Then you can style the divs as you want, allowing text wrapping, etc. This also works well with an unordered list.
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