Which fruit has the biggest seed?

Hint: Fertilization produces seeds and fruits. In angiosperms, double fertilisation produces two structures: a diploid zygote and a triploid main endosperm cell. While the zygote develops into an embryo, the endosperm cell produces endosperm cells. It offers food for the developing embryo. Angiosperms are composed of both fruits and seeds.
Significance of seed formation:
Dependable method
Perrenation
Dispersal
Reserve food
Variations
Storage

Complete answer:
Coconut on top of coconut.
The double coconut fruit, also known as Lodoicea maldivica or coco-de-mer, is noted for producing the world's heaviest and largest seeds. It has a maximum weight of eighteen kilograms and a length of twelve inches. The seed resembles a dark brown colossus.
The seed of the Lodoicea maldivica plant, often known as "the double coconut", is a gigantic fan palm that grows to a height of twenty-five meters. The palm can only be found on two Seychelles islands: Praslin and Curieuse. The palm is most renowned for the world's largest seed, which is found in its fruit.
Seeds that had germinated (and so been hollowed out) would find their way into the water, where they would be carried to the Maldives by the prevailing sea currents. Indigenous populations on the islands used the seeds for medical purposes and for trade.

Note:
The coco de mer seed is enormous and hefty, with a form that is strikingly similar to a pair of female buttocks. These two characteristics have earned the seed a unique place on the globe.
The coco de mer seed is the subject of at least two strange legends because it resembles a pair of feminine buttocks while the male bloom is phallic in appearance. According to the first legend, when no one is looking, the male and female trees get together for nights of passion. Anyone who truly witnesses the love-making is blinded or dies. According to the second version, when British Army Major General Charles George Gordon first saw coco de mer seeds, he mistook them for the forbidden fruit offered to Adam by Eve in the Garden of Eden.