Why/How

[sitifan]

Tom: ____ did Elaine know about sky lanterns? Gina: She read some information on the Internet.
(A) Why (B) What (C) How (D) Who
The given answer is C. Is option A acceptable?

http://en.wikipedia.org/wiki/Sky_lantern

[5jj]

No. In the unlikely event of the question being asked, we would expect a reason as an answer, not an explanation of how.