Which of the follow describes the author's main purpose in the text?

A.
to inform readers about the important discovery made by a female cryptanalyst

B.
to teach readers about the process of coding and decoding messages

C.
to emphasize the various jobs that women could have during World War II

D.
to show the obstacles that Grotjan faced as a female cryptanalyst

D. to show the obstacles that Grotjan faced as a female cryptanalyst