Hello @keepRunning and welcome to the GreenSock Forum!
Yeah browsers wont even let you style specific CSS for <option> HTML elements. Chrome or other webkit based browsers used to allow CSS to style both <select> and <option> elements, but they have been pretty poopy pants about styling <option> tags lately. So the browser will reject certain CSS properties for visual, layout, and transforms on <option> tags. The HTML DOM interface won't allow it. The browsers only allow things like font-size, font-family, font-variant, font-style, color, background-color, background, etc like Blake said above
When i look at the spec for <option> tags there is no mention of this
Only other route is like Sahil advised is where the original <select> tag is hidden. And then you create a custom dropdown with animated option tag using <ul> and <li> tags.. or use a jQuery UI dropdown select that is jQuery custom HTML.