She goes by herself

(Originally written by the user 'sergeantc')

Isabel called some of her friends, but no one was free. She seemed to be the only one who had the day off.

Isabel thought about it for a while, then decided to go to the beach by herself. She could still get a tan and go for a swim, and who knew: she might find it easier to meet a cute guy there.

Isabel spent the next twenty minutes or so gathering together all the things she expected to need -- sunglasses, sandals, and so on.

When that was done, she headed for her bedroom. She still had one decision to make.

She had her regular bikini, which had a string top and a Brazil cut bottom. It had taken her a while to get used to what she considered a rather revealing top, but now she could wear it with few worries. She had the new strapless bikini with the G-string bottom she had bought on an impulse a month ago and hadn't had the nerve to wear yet.

Or she could do what she sometimes did, wear her old black bikini bottom with a cut-off white t-shirt.

Which swimsuit does Isabel wear?