That is why they include a picture with each option choice. The picture shows you what "cropped and capri" mean.
Well, this captcha doesn't looks that easy from first sight, but as said above, there is little image for every option which shows how capri or 7/8ths looks.
But I think that you can switch to Google Recaptcha on that Wheel of Fortune page. At least I'm getting ReCaptcha always and I don't have to struggle with captcha for fashion designers

.
Sure, you have those examples, but still, i see very little difference between full length and 7/8 length (especially if it's just the pants that are being shown). Same for 7/8th and capri.
Same for capri and below the knee.
It's not rare for me to have to retry the captcha 2 or 3 times....
All in all, i'm not mad about this... It's a free site, it does it's job, it's fun, i have nothing to complain since i get to use it for free... That being said, i still think that a captcha for fashionista's might not be pointed at the right target audience for a site like freebitco.in.
@LTU_btc: i'll have a look if i find something in the settings about the captcha... I did look briefly, but maybe i overlooked (this happens quite often with me).