The correct option is C Spore
The prothallus is developed from a spore. Prothallium, or prothallus is usually the gametophyte stage in the life cycle. The prothallium develops from a germinating spore. It is a short-lived and inconspicuous heart-shaped structure typically 2-5 millimeters wide, with a number of rhizoids (root-like hairs), growing underneath, and the sex organs: archegonium (female) and antheridium (male).