Why Did So Many Researchers Make One Individual, Henry Molaison

Why did so many researchers make one individual, Henry Molaison, the subject of their research?

A) He was unusually insightful in how he described his thought processes, so he became the focus of many case studies.
B) Molaison had incredibly fast reflexes, which made him one of a kind.
C) He was so neurotypical in his responses that scientists could study just him instead of hundreds of other people.
D) Molaison had an unusual illness that caused him to undergo risky surgery, so there were few other subjects like him.