What is the greatest positive integer x such that 4^x is a factor of 64^10?	Options:	A) 5	B) 9	C) 10	D) 20	E) 30
64^10 = (4^3)^10 = 4^30   ANSW30R:30
<result>E</result>
What is the greatest positive integer x such that 4^x is a factor of 64^10?