Answer:
d. hippocampus.
Explanation:
The hippocampus is where episodic memories are formed and stored to use later. This kind of memories are autobiographical, this means that they are formed from our experiences, for example Mr. Yanagita learning to play poker. We conclude the hippocampus is damaged because Mr. YAnagita can't recall the experience of having played poker before.
I hope you find this information useful and interesting! Good luck.