Which part of the vertebrate brain develops from the embryonic diencephalon

The diencephalon gives rise to posterior forebrain structures.

Explanation:

The diencephalon developes forebrain structures and present in the neural tube of vertebrate. Prosencephalon is present in the anterior part of neural tube that developes the forebrain which further forms the diencephalon and the telencephalon.

The diencephalon is located at the upper end of brain between the cerebrum and the brain stem. Diencephalon has four components the thalamus, the hypothalamus, the subthalamus, and the epithalamus.

Diencephalon performs vital functions including regulating wakefulness and control the autonomic nervous system.

So, the diencephalon developes forebrain structures.