Read the passage and answer the following questions .

The primary cell of the endosperm undergoes repeated divisions, resulting in the formation of a triploid endosperm tissue. This tissue contains reserve food materials that serve as nutrition for the developing embryo. The most common type of endosperm development involves the successive nuclear divisions of the primary endosperm cell, leading to the formation of free nuclei. This stage is known as the free-nuclear endosperm. Eventually, cell wall formation occurs, and the endosperm transitions into a cellular state. The number of free nuclei formed before cellularization varies significantly. In the case of tender coconuts, the liquid known as coconut water is composed of a free-nuclear endosperm consisting of thousands of nuclei, while the surrounding white kernel represents the cellular endosperm. Endosperm can either be fully consumed by the developing embryo before seed maturation (e.g., pea, groundnut, beans) or persist in the mature seed and be utilized during seed germination (e.g., castor and coconut). By observing the seeds of castor, peas, beans, groundnut, and coconut, one can identify the presence of endosperm in each case. The embryo develops at the micropylar end of the embryo sac where the zygote is located. Zygotes typically divide after a certain amount of endosperm is formed, ensuring reliable nutrition for the developing embryo. Although seeds differ greatly, the early stages of embryo development (embryogeny) exhibit similarities between monocotyledons and dicotyledons. A typical dicotyledonous embryo consists of an embryonal axis and two cotyledons. The epicotyl, located above the cotyledons, terminates with the plumule or stem tip. The cylindrical portion below the cotyledons is called the hypocotyl, which ends with the radicle or root tip. The root tip is protected by a root cap. In contrast, embryos of monocotyledons possess only one cotyledon, referred to as the scutellum in the grass family. The scutellum is positioned laterally to the embryonal axis

Which stage of endosperm development involves the formation of free nuclei?

Free-nuclear endosperm

The correct answer is Option (1) – Free-nuclear endosperm

In free-nuclear endosperm, the primary endosperm nucleus undergoes repeated rounds of mitosis without cytokinesis. This results in a mass of free nuclei in the cytoplasm of the endosperm. Eventually, the nuclei become surrounded by cell walls, and the endosperm becomes cellular.

Cellular endosperm, on the other hand, is formed when the primary endosperm nucleus undergoes mitosis and cytokinesis simultaneously. 

The number of free nuclei formed before cellularisation varies greatly. The coconut water from tender coconut that you are familiar with, is nothing but free-nuclear endosperm (made up of thousands of nuclei) and the surrounding white kernel is the cellular endosperm.

Helobial Endosperm: This type of endosperm development is common in monocotyledons. The first division is similar to cellular endosperm and results in a large micropylar cell and small chalazal cell. The chalazal cell mostly does not divide further and functions as a base cell. The micropylar cell divides further, similar to nuclear endosperm. So helobial is an intermediate type, a combination of both nuclear and cellular endosperm.