The correct answer is Spores

Fern plants reproduce by spores. Spores are small structures that are produced on the undersides of fern fronds, which are the leaves of the fern plant. When these spores are mature, they are released into the air and can be carried by wind or water to new locations. If the conditions are right, the spores will germinate and grow into new fern plants. This method of reproduction is different from seed reproduction, which involves the production of a seed that contains an embryo and stored nutrients to support the growth of a new plant.