What is the most significant limitation that carl schurz’s work has, as a resource for a historian?

He wrote his account about fifty years after the events occurred.

What is the most significant limitation that Carl Schurz’s work has, as a resource for a historian?  

He was not an eyewitness to the events he describes.  

He was too young to be a reliable witness.  

He was an employee of the government and likely biased against the revolutionaries.  

He wrote his account about fifty years after the events occurred.

D.He wrote his account about fifty years after the events occurred.

#1 im pretty sure its a.

is this question from a book? ?