单选题：The problem with the optimal page replacement algorithm is _____
The problem with the optimal page replacement algorithm is _______.@[D](1)
A. it runs too fast and may miss some pages.
B. it runs too slow and there are faster alternatives that work well enough.
C. it only works with very expensive hardware.
D. it cannot be implemented.
A.it runs too fast and may miss some pages.
B.it runs too slow and there are faster alternatives that work well enough.
C.it only works with very expensive hardware.
D.it cannot be implemented.
答案：D
A. it runs too fast and may miss some pages.
B. it runs too slow and there are faster alternatives that work well enough.
C. it only works with very expensive hardware.
D. it cannot be implemented.
A.it runs too fast and may miss some pages.
B.it runs too slow and there are faster alternatives that work well enough.
C.it only works with very expensive hardware.
D.it cannot be implemented.
答案：D