What should I buy for my girlfriend to wear ?

I would go with B. I think a girl would feel more y in panties then in a skirt. The bra on the on B. would also provide comfort since the hanging cloth would stimulate her skin on the area and/or if she's uncomfortable of about her waist line she will have something to make her feel better. Although her waist line in reality isn't anywhere close to what she thinks and shouldn't be uncomfortable about it at all.