What is the greatest positive integer x such that 3^x is a factor of 9^10? Choose the correct option
A) 5 B) 9 C) 10 D) 20 E) 30
9^10 = (3^2)^10 = 3^20   The Answer is D. 20
<result>D</result>
What is the greatest positive integer x such that 3^x is a factor of 9^10?