I'm leaning hardest for option 3, but her clothing and body changing together over the bimbo levels. So like once her breasts become large enough to render her school jacket useless to cover up anything she'll go without, or her skirt becomes short enough so she can show off the full length of her stockings so she starts wearing them longer. As for her hair or accessories, I'm pretty neutral on those, although I do like the look of the huge top-right ponytail.