Arrange asymptotic efficiency classes in increasing order of magnitude.
a) O(n), O(n log n), O(n²), O(1)
b) O(n log n), O(n), O(1), O(n²)
c) O(1), O(n), O(n log n), O(n²)
d) O(1), O(n log n), O(n), O(n²)