The correct answer is Option 1: Egg → zygote → embryo → seed.

Detailed Step-by-Step Sequence:

During sexual reproduction in flowering plants (Angiosperms), the development follows a strict chronological order:

Egg (Gamete): The process begins with the female gamete, known as the egg cell, which resides inside the ovule of the flower's ovary.

Zygote (Fertilization): A pollen grain lands on the stigma, grows a pollen tube down to the ovule, and releases male gametes. One male gamete fuses with the egg cell in a process called fertilization, creating a single-celled, diploid zygote.

Embryo (Development): The zygote undergoes repeated cellular divisions (mitosis) and differentiation to transform into a multicellular embryo (the miniature, undeveloped plant).

Seed (Maturation): As the embryo develops, the surrounding tissues of the ovule harden to form a protective coat. The entire structure matures into a seed, which houses the embryo and its food supply until conditions are right for germination.

Why the other options are incorrect:

Option 2 & Option 3: These put the embryo before the zygote. An embryo cannot form without the single-celled zygote dividing first.

Option 4: This suggests that a seed is formed before a zygote or an embryo develops, which is biologically backward; the seed is the final product that encloses the developed embryo.