For each function below, let n be the least integer such that f(x) is O(xⁿ). Arrange the functions in increasing order of n:
A. f(x) = 3x³ + (log x)⁴
B. f(x) = (x⁵ + x² + 1)/(x³ + 1)
C. f(x) = (x³ + x² + 1)/(x² + 1)
D. f(x) = (x² + 5 log x)/(x² + 1)
Choose the correct answer from the options given below:

1. AD, C, A, B
2. BD, C, B, A
3. CB, C, A, D
4. DB, A, C, D

Pick an option to check yourself, or open the answer below.