If the partial order of a set has at most one minimal element, then to test whether it has a non-crossing Hasse diagram its time complexity __________

If the partial order of a set has at most one minimal element, then to

1.	If the partial order of a set has at most one minimal element, then to test whether it has a non-crossing Hasse diagram its time complexity __________
A.	NP-complete
B.	O(n²)
C.	O(n+2)
D.	O(n³)
Answer» B. O(n²)