Which one of the following is the characteristic feature of gymnosperms?

To identify the characteristic feature of gymnosperms, let us break down the terminology and botanical characteristics of this plant group:

1. Etymology of the term:
The word "Gymnosperm" is derived from two Greek words:
• Gymnos meaning "naked"
• Sperma meaning "seed"
Thus, the term literally translates to "naked seeds".

2. Anatomical basis:
Unlike angiosperms (flowering plants), gymnosperms do not possess an ovary wall that encloses the ovules. The ovules are exposed on the surfaces of specialized leaves called megasporophylls (which typically form cones). Because there is no ovary to develop into a fruit after fertilization, the resulting seeds remain exposed or "naked" on the scale of the cone.

3. Evaluating the options:
• Seeds are enclosed in fruits: This is the defining characteristic of angiosperms, not gymnosperms.
• Seeds are naked: This is the primary characteristic feature of gymnosperms.
• Seeds are absent: Gymnosperms are seed-producing plants (spermatophytes), so seeds are present.
• Gymnosperms have flowers for reproduction: Gymnosperms do not produce flowers; they reproduce using cones (strobili).

Therefore, the characteristic feature of gymnosperms is that their seeds are naked.