When a moss spore lands in a suitable spot, it germinates and grows into a filament of cells called a:

A) seta.
B) archegonia.
C) megaspore.
D) protonema.
E) prothallus.

Protonema

A thread-like chain of cells that forms the earliest stage of a moss or fern life cycle, emerging from the spore and developing into the gametophyte.

Moss Spore

A reproductive unit capable of developing into a new moss plant, produced by mosses as a part of their life cycle.

Filament

A thin, thread-like structure, often part of a larger network, used in various biological and industrial contexts.