单选题：Consider a page reference string for a process with M frames, in

Consider a page reference string for a process with M frames, initially all empty. The length of page reference string is L with D distinct page numbers in it.
What is an upper bound on the number of page faults? @[C](1)
A. M
B. L-D
C. L
D. D+M




A.M
B.L-D
C.L
D.D+M


答案：C