Gemmules are the asexual structures of:

Sponges

The correct answer is Option (4) → Sponges

Members of the Kingdom Fungi and simple plants such as algae reproduce through special asexual reproductive structures . The most common of these structures are zoospores that usually are microscopic motile structures. Other common asexual reproductive structures are conidia (Penicillium), buds (Hydra) and gemmules (sponge).

Gemmules are internal buds found in sponges and are involved in asexual reproduction . It is an asexually reproduced mass of cells, that is capable of developing into a new organism i.e., an adult sponge.

Many single-celled organisms reproduce by binary fission, where a cell divides into two halves and each rapidly grows into an adult (e.g., Amoeba, Paramecium).