In ferns the spores develop on A. the tip of the gametophyte. B. the underside of the gametophyte. C. the roots of the gametophyte. D. the underside of the sporophyte.

The correct answer is option D-the underside of the sporophyte.

Explanation:

Ferns are pteridophytes which evolved earlier than the flowering plants. They do not produce seeds and reproduce through spores.

These spores are usually present on the underside of fern leaf also called "fronds" in sporophytic structures called sori. When these spores are ripened they are released from the capsule which germinates to produce prothallus, a gametophyte from which gametes are produced.

Thus, option D-the underside of the sporophyte is the correct option.

Roots of the gametophyte spores develop