(b) embryo

Explanation:

The plant which consists of two generations one within the other is embryo. In botany, a seed plant embryo is part of a seed, consisting of precursor tissues for the leaves, stem and root as well as one or more cotyledons. Once the embryo begins to germinate, grow out from the seed, it is called a seedling. Plants that do not produce seeds, but do produce an embryo, include the bryophytes and ferns. In these plants, the embryo is a young plant that grows attached to a parental gametophyte.