Final answer:
The hypothalamus can influence aggression through projections to the amygdala and pituitary gland, which are involved in emotional responses and hormonal control, respectively (option a and d).
Step-by-step explanation:
The hypothalamus can influence aggression through projections to various parts of the brain. Specifically, the hypothalamus has connections with the amygdala, which is a group of nuclei in the medial region of the temporal lobe. The amygdala is associated with emotional responses and has a strong effect on the hypothalamus, informing it about emotional states and potentially stimulating autonomic and endocrine responses related to aggression.
The pituitary gland is also influenced by the hypothalamus and can be involved in aggression as it contributes to the release of various hormones that can affect behavior. For example, in response to signals from the amygdala, the hypothalamus can stimulate the release of stress hormones through its control of the endocrine system. Therefore, projections to both the amygdala and pituitary gland are involved in the hypothalamic influence on aggression.
While the hippocampus is involved in memory and the limbic system to which it belongs is associated with emotional responses, and the medulla oblongata is part of the brainstem overseeing automatic functions, they are not as directly tied to the hypothalamus' influence on aggression through projections as the amygdala and pituitary gland are.
Hence, the answer is option a and d.