The correct option is A Bryophyta
Thallophyta group contains plants, which do not have well differentiated plant body.
Angiosperm contains plants, which have well differentiated plant body as well as seeds inside their fruits.
Gymnosperm contains plants, which have well differentiated plant body but have naked seeds.
Bryophytes do not have well differentiated plant body into stem, leaf like structure and roots. They do not have true stem, leaf and roots.