The following excerpt is from a book about the discovery of a Neanderthal skull in Belgium: "As Dr. Fuhlrott has not yet published his description of these circumstances, I borrow the following account of them from one of his letters. 'A small cave or grotto, high enough to admit a man, and about 15 feet deep from the entrance . . .exists in the southern wall of the gorge of the Neanderthal, . . . about 60 feet above the bottom of the valley.'"
—On Some Fossil Remains of Man by Thomas H. Huxley

Which of the following best describes the account from the letter excerpt?

It is a primary source because it was written by someone who was present at the discovery of the skull.
It is a secondary source because it was written after the discovery of the skull was made.
It is a primary source because it provides an accurate description of the caves where the skull was found.
It is a secondary source because it appears in a textbook printed years after the discovery.