Final answer:
The correct answer is b) H.M.'s episodic memory was impacted, but his procedural memory was intact. We learned from H.M. that the hippocampus is crucial for consolidating short-term memories into long-term, especially declarative memories, but it is not required for the formation of procedural or implicit memories.
Step-by-step explanation:
From the well-documented case of H.M., we have learned significantly about the role of the hippocampus and different types of memory. The option b) H.M.'s episodic memory was impacted, but his procedural memory was intact, is the correct answer. H.M. was unable to form new episodic or semantic memories —collectively known as declarative or explicit memories— due to surgery that removed his hippocampus and amygdala to treat severe epilepsy. However, H.M. could form new procedural or implicit memories, such as learning how to solve a puzzle without the recollection of ever doing it before.
Further studies determined that the hippocampus is essential for the consolidation of short-term memories into long-term storage, particularly for explicit memories. As for H.M., while his ability to form new short-term memories remained intact, he could not consolidate these into long-term memories due to the removal of the medial temporal lobe structures that included the hippocampus.