Passage: The sexually dimorphic nucleus (SDN) is an ovoid, densely packed cluster of large cells located in the medial preoptic area (POA) of the hypothalamus which is believed to be related to sexual behavior in animals.

Question: Based on this passage, the sexually dimorphic nucleus is part of the ____.?
Steam of consciousness below:
The important part for answering this question is: The sexually dimorphic nucleus (SDN) is an ovoid, densely packed cluster of large cells located in the medial preoptic area (POA) of the hypothalamus which is believed to be related to sexual behavior in animals.
So, the answer is the medial preoptic area ( POA ) of the hypothalamus.