What is the greatest prime factor of 10!9! + 9!8! ?	Choose the correct choice from the following options
A) 7  B) 11  C) 13  D) 17  E) 19
10!9! + 9!8! = 9!8!(10*9+1) = 9!*8!*91 = 9!*8!*7*13   The answer is 13.
<result>C</result>
What is the greatest prime factor of 10!9! + 9!8! ?