Explanation:

Gymnosperms:
Gymnosperms are a group of seed-producing plants that includes conifers, cycads, Ginkgo, and Gnetales. They are characterized by the presence of naked seeds, which are not enclosed in an ovary or fruit.

Reason for not bearing fruits:
The correct answer is option A, which states that gymnosperms do not bear fruits because they do not have ovaries. This is because fruits are the mature ovaries of flowering plants, which contain seeds. In gymnosperms, the seeds are not enclosed within an ovary, but are instead exposed on the surface of specialized structures called cones or strobili.

Structure of gymnosperm cones:
Gymnosperms produce cones or strobili, which are reproductive structures that contain the male and female reproductive parts. These cones can be of two types - male cones and female cones.

1. Male cones: The male cones of gymnosperms produce pollen, which contains the male gametes. The pollen is released into the air and can be carried by wind or insects to reach the female cones.

2. Female cones: The female cones of gymnosperms contain ovules, which are the structures that house the female gametes. The ovules are not enclosed within an ovary, but are exposed on the surface of the cone scales. When the pollen reaches the female cones, it lands on the exposed ovules and fertilization occurs.

Fertilization and seed development:
After fertilization, the ovules develop into seeds. The seeds of gymnosperms are not enclosed within a fruit, but are exposed on the surface of the cone scales. This is in contrast to flowering plants, where the seeds are enclosed within a fruit.

Conclusion:
In conclusion, gymnosperms do not bear fruits because they do not have ovaries. Instead, they produce cones or strobili, which contain the male and female reproductive structures. The seeds of gymnosperms are not enclosed within a fruit, but are exposed on the surface of the cone scales.