Final answer:
The diencephalon, including the thalamus and hypothalamus, serves as a relay for sensory information and regulates body temperature and CSF secretion.
Step-by-step explanation:
The diencephalon, which includes the thalamus and the hypothalamus, serves a variety of important functions. It acts as a relay between the cerebrum and the rest of the nervous system, allowing for the processing and transmission of sensory information. Additionally, the hypothalamus in the diencephalon regulates body temperature and secretes cerebrospinal fluid (CSF). Therefore, the correct answer is 4) All of these are functions of the diencephalon.