Hotaka can vividly recall the devastating experience of barely surviving the tsunami that took the lives of many others. it is likely that the stress of that experience provoked the to boost activity in the memory-forming areas of his brain.
(a) hypothalamus
(b) cerebellum
(c) thalamus
(d) amygdala

(D) amygdala.

Explanation:

Situations that are particularly emotionally draining or stressful are very likely to become long-lasting memories.  Arousing or extremely anxious situations can activate the Amygdala´s limbic system,  increasing activity in the memory-forming regions of the brain. 

Stress hormones discharged by the adrenal glands are vital for the consolidation of emotionally exciting or shocking memories. 

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