Coconut water from a tender coconut is Degenerated nucellus. Immature embryo. Free nuclear endosperm. Innermost layers of the seed out.

Tender coconut water is a clear liquid found inside of the young tender coconut. During the nuclear phase of the development, it provides as a termination for the endosperm of the coconut. In the nuclear endosperm formation, free-nuclear divisions are repeatedly done; if a cell wall is developed it will form after free-nuclear divisions. Commonly referred to as liquid endosperm. Coconut water from a tender coconut is an example of this process i.e, free nuclear endosperm. So, the correct answer is option D.