page replacement

Question

A page-replacement algorithm should minimize the number of page faults. We can achieve this minimization by distributing heavily used pages evenly over all of memory, rather than having them compete for a small number of page frames. We can associate with each page frame a counter of the number of pages associated with that frame. Then, to replace a page, we can search for the page frame with the smallest counter.
How many page faults occur for the above algorithm for the following reference string with four page frames? 
1, 2, 3, 4, 5, 3, 4, 1, 6, 7, 8, 7, 8, 9, 7, 8, 9, 5, 4, 5, 4, 2.

	(A) 11
	(B) 12
	(C) 13
	(D) 14

Comments

according to problem statement, i think it is using "least frequently used" replacement algorithm, but using it we can get multiple answer, one answer i am getting as 

D) 14..

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There are certain ambiguity in question

1) Each frame is maintains counter of number of pages associated, so initiallyeach counter is reset after first 4 misses all counter will have value 1 now if next new page comes it can go to any of frame so how to break tie ?

2) If an page was previously associated with frame 1, now after some time page is not in frame and as per policy we assign to say frame 3 so we should increment frame 3 counter by 1 but what about frame 1 counter ?

3) In what sense even distribution is considered here ?

Answer 1

In some source, they have by default assumed FIFO policy for breaking ties. So if FIFO is considered for breaking ties then the number of page faults must be 13.

Comments

so, what assumptions we need to take to solve this question Fifo, lru?