A seed is a fertilized ovule containing the plant embryo. Given the appropriate growth conditions, it will become the new plant. Thus, it is also regarded as the propagating organ particularly of spermatophytes (i.e. gymnosperms and angiosperms). Plants such as ferns, mosses, and liverworts do not produce seeds.

Seed refers to the fertilized, matured ovule that contains embryonic plant, stored material and a protective coat or coats.
A seed is a mature ovule that comprises an embryo or a miniature undeveloped plant and food reserves, all enclosed within a protective seed coat. Seeds are a way of reproduction for all flowering plants. Every seed is capable of growing into a new plant, under proper environmental conditions such as the right temperature, moisture and sunlight.

Seed is defined as:

A) Mature integumented spore
B) A mature dormant integumented megasporangium
C) An immature integumented ovule
D) An immature integumented ovary

The correct answer is option B, which states that a seed is a mature dormant integumented megasporangium.

Explanation:

A seed is the reproductive structure of a flowering plant. It contains the embryonic plant, along with a food source and a protective coat. The development of a seed begins with the formation of an immature ovule within the ovary of a flower.

Formation of Seed:

1. Pollination: Pollination occurs when pollen from the male reproductive organs (anther) is transferred to the female reproductive organs (stigma) of a flower.

2. Fertilization: After pollination, the pollen grain germinates on the stigma and forms a pollen tube. The pollen tube grows down the style and reaches the ovary, where it enters the ovule through a small opening called the micropyle. The male gametes (sperm cells) are released from the pollen tube and fertilize the female gametes (egg cells) within the ovule.

3. Development of Embryo: After fertilization, the zygote is formed, which divides and develops into an embryo. The embryo consists of the embryonic axis (root and shoot) and one or two cotyledons (seed leaves).

4. Maturation of Seed: As the embryo develops, the ovule undergoes various changes and becomes a seed. The integuments of the ovule develop into a protective seed coat, which encloses the embryo and the endosperm (food source).

5. Dormancy: Once the seed matures, it enters a dormant state. Dormancy is a period of arrested development, during which the seed remains inactive and does not germinate. This dormancy helps the seed to survive unfavorable conditions until it encounters suitable environmental conditions for germination.

6. Dispersal: Seeds are dispersed to new locations by various means such as wind, water, animals, or humans. This dispersal mechanism allows plants to colonize new areas and avoid competition with parent plants.

Conclusion:

In conclusion, a seed is a mature dormant integumented megasporangium. It is formed from an immature ovule within the ovary of a flower. The seed contains the embryonic plant, a food source, and a protective coat. The process of seed formation involves pollination, fertilization, development of the embryo, maturation of the seed, dormancy, and dispersal.