Suppose we have a circular queue where we choose to leave one empty cell. Which of the conditions is a test for an empty queue?

self.$\_$tail $==($self$.\_$head $-1)$

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self.$\_$head $==$ self.$\_$tail

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$($self$.\_$tail $-$ self.$\_$head$)==$ self.$\_$capacity

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self.$\_$head $==($self$.\_$tail $1)$

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