In which type of development embryo sac formation from a single megaspore takes place?

In monosporic development.

The correct answer is Option (1) –In monosporic development.

In monosporic development, the embryo sac is formed from a single megaspore. This is the most common type of embryo sac development in flowering plants.

In tetrasporic development, the embryo sac is formed from four megaspores. This type of development is less common, and it is only found in a few species of flowering plants.

In bisporic development, the embryo sac is formed from two megaspores

Therefore, the answer is monosporic development.