The correct answer is option 1: Endosperm. The endosperm is the part of the coconut that is edible. It is the innermost layer of the coconut and is usually white and firm. The endosperm is rich in nutrients and is commonly consumed as coconut meat or used to make coconut milk and oil.

Option 2, Mesocarp, refers to the fleshy and fibrous middle layer of the coconut, which is not typically eaten. Option 3, Endocarp, is the hard shell of the coconut, which is also not edible. Option 4, Exocarp, refers to the outermost layer of the coconut, which is the husk. This part is also not edible and is usually removed before consuming the inner endosperm.